Larry it is wise to look at the underlying investments of the fund, the M & G fund you mention is, I believe in more risky stocks, the M & G website would tell you more, a fund of blue chips is safer but returns will be less. The share you mention is around 89p and due to wind-up in march at 100p, how they get 45% I dont know.
Most funds use the money in zeros as gearing and this is why they dont usually pass money to the zero fund until wind-up date, however not all funds have a wind-up date.
One other thing to consider is the bank base rate, a zero paying 5% now seems good but if base rates rise the your share will be worth less. If you think this is likely then buy one with a short date, most splits start with an end date of 5-10yrs. Hope this helps, you may find the 'Trustnet' website useful.