But in the meantime, you are 100% exposed to the hypothetical "nightmare tenant".

I'm not. I'm fireproof. 20+ years and counting. Believe me, I've seen it ALL...

Cannabis farms [a helpful tenant destroyed it, without me being any the wiser, only telling me months later]
Abstraction of electricity [& abstracted electricity run from one flat to another via a wire !]
Drugs raids
A tenant taking a tenancy, purely to run the flat as a drugs den for his mates, courtesy of the benefits system.
"Cuckooing" and "Ghosting".
Good tenants leaving because of the above.
Flood because the tenant fled due to cold - she only had a gas fire as the sole source of heat*; her flat iced up (no heat, as she helpfully switched everything off), then thawed and burst onto the one below, destroying it.
More...

*I of course waited until I could install central heating under a grant, free of charge, courtesy of the tax-payer.

True but these are the precise reasons why I buy decent houses.
Look for professionals such Doctors, Dentists etc (where there is reputational risk for them), or professional couple who has moved to get access to the nearby good school for their kids and potentially save on private school fees.

This could include overseas professionals who have secured employment/contracts s in one of the locally based muti-national corporations (research, IT contracts etc). Even better if their employer just pays me - no issues with annual rises and this can be more than the private rental sector.

Even had one employer take property for 3 years and ensured property was returned just as it was when they signed the tenancy.

I also take out insurances to cover myself.

I've also positioned myself in a spot where most of my tenants want to move up ie go to a bigger and better house and in a more affluent part part of town where their kids school friends live (ie £1m + properties).

This way I get to avoid the hoi polloi and the baggage they bring. For me the vetting is very important. I want to know the job they do (more so than the salary they earn as most of my tenants are HRT or ART individually).

I want my agents to ascertain soft things like
- their educational background and what, were they studied.
- whether earnings or career is more important
- how long they have been in their current role (and relationship)
- their attitude towards family
- which school they want to send their kids to and if it is important
- etc etc.

The hard factual things can be done on a desk and can be insured against but the soft things needs to be done at multiple meets, viewings (despite plenty of offers without any viewing which is the norm here, I will never accept a tenant who has not met with the agents or viewed the property), interviews, references personally checked on top of standard desktop ones.

Not sure how much I have made but details of some of the latest holdings which I have had to tinker with.

Last Completed sale
Purchase price - £174k (£26k deposit / outlay)
Sale Price - £325k
Gross Capital Gain after expenses - £144k
CGT - £37k
Net Capital Gain - £107k Gain
Rental Gain during hold period - £40k
Total Gain £150k or 6k on original deposit
Twist benefit - kept side garden for a potential 2 bed bungalow £150-200k outlay £300k sale
Thus Extra £100k conservative extra

Current Hold
Purchase price £216k (£52k deposit)
Current Price - £450k on a bad day (agents put it circa £475-£500k)
Gross capital gain - £234k
Net Capital Gain (after CGT allowances) - £174k
+ Rental Gain during hold - £69k
Total Potential Gain as is - £243k
Twist benefit - Currently 3 bed semi with side garage.
Potential knock down of garage and put 2 storey wrap around at cost of circa £175 - £200k
Potential sale £800k (neighbor did similar and sold for £850k - £25k below asking)

Current Hold
Purchase price £48k (1988)
Current Valuation - £500k
Gross Capital Gain - £ £450k
+ Rental Gain - £156k
3 Bed semi (only by name) can only add loft conversion - will add circa £70 - £100k if remodeled)

Current Hold
Purchase price £150k
Current Valuation £300k
+ Rental Gain - £69k

Currently Going through
Purchase price £185k (23k deposit)
Agreed Part sale (keeping separate garage and garden behind garage £325k
Net Capital Gain - £140k
Capital Gain after CGT (3) - £84k
+ Rental Gain - £32k
3 Bed semi with large side plot and separate garage which can be knocked down and like opposite neighbor can put up a 3 bed detached (in name as no real land left apart from rear and front.) Previous owner kept rear half of garden which adjoins road on side and built themselves a 5 bed detached.

These are the notable ones of mention but not all of them currently in portfolio there are two with no mortgages. Rest have mortgages all below 50% LTV. That too because I decided to release equity in 2020 and buy a couple more a 3 bed semi and a 2 bed coach house.

Majority of my sales over the years have been to my tenants and for many properties, I rarely set foot in after the keys are handed to agents even though 2 are round the corner from me (though I always keep rental properties in the UK local but never meet the tenants - was shocked when a tenant bumped into me in town and introduced themselves as my tenant did not feel right and politely pointed them towards the agents).

There is a plot round the corner where a 3 bed detached with 2 separate garages sit by the side _ more and very large long rear garden on market for £750k. Agent has stated the developers have already pushed it over £900k - plan is to knock it down and build two decent 4 bed houses and market them for over a £1m each - they will sell easily.

I do remember the first property of mine bought for £30k sold for £110k (panicked on fear breakup and other half coming after asset). Also remember my parents having lots of issues with DSS tenants and properties in bad neighborhoods - so completely avoid all that.

For me BTL investing is more about a store of wealth as opposed to anything else. It is there if my offspring or family run into difficulties. If they fall off the rails they get nothing

Friends of parents bough a bought a house £2k (I was told this so not verified) in the late 70's and recently sold for £850k but will loose it all for care costs.

Very lots of food for thought here as a newbie. I was initially attracted to Find UK properties as they acquire, refurbish, tenant and have guaranteed rentals although yields are 5/6% and the market value they sell to you are massive overpriced, like Homes Under The Hammer on steroids (they are proud of appearing five times but dont get an agent evaluation at the end of the refurbishment process - they just pin it to a tier of prices). Many of the lower end properties (70-90k) are in undersireable streets. I don't like it all now.
Conversely, a one bedroom bungalow in need of some cosmetics has become available in our Cheshire village for 100k - that's cheap round here.
My next question is finance. I have 70k cash - can you get a mortgage for 30k? or how about a bridging loan but they look pretty expensive.