if you have a house that is say worth £150000 and you own 25% thats £37500 of money you can raise to use for what you wish.
As you want a buy to let,you would search for a buy to let mortgage to buy a property to let out,
lets say you find a house to let out and it costs you £145000, you will find most buy to lets offer a LTV of say 60% so will lend you £87000 so you will need to find £58000
as you will have raised £37500 from your home you will still need £20500 !
you will need to use your own figures,but this is how it works.
Even if your buy to let say costs £100k and you get a 60% LTV(loan to value) you will still need to find £40k less what you have raised on your home £37500 so still need £2500
All this depends on what valuations you get for your own home to work out what they will lend you.
On top of this you will have fees,insurance,vetting tenants etc,gas certificates to worry about
the list goes on,so be aware.
Also they will want the house you are buying to let out to be valued as you are raising a mortgage on it,they may say the house is worth only £95k if so thats all you want to pay the owner ! this will then be £95k x 60%=£57000 leaving you to find £38000 less what you have raised on your home £37500 so you will still need to find £500
moral is, to buy something that will fall into what you can afford.
You cannot raise a buy to let on your own home,you can raise money to invest into another property.The only way to let your own property is to move out and tell your mortgage company or they may want you to take out a buy to let on it as this will become a buy to let,
but where do you live ? hope this helps.