Lets start with 17.5% VAT on the total cost of the parts including the cost of transport and the mandatory 8130-3.
The A & P won't get £40/hour that is the rate that the shop will charge and the A & P is likely to be making about £14-18/hour.
The $ rate has started to help but the real problem is the local and national goverment taxes, fuel has a tax called "duty" and then on top of the fuel cost+duty they put 17.5 % VAT so 100LL costs about $8/USG.
The cost of living numbers are about the same......... it's just the $ is worth half as much!
EASA is making it mandatory for all aircraft maintenance to be done by "approved" companys so the day of the indipendent A & P are numbered.
(American English used for the benifit of White bear)