I asked a similar 'what if' question (not on Pprune I might add) a year back.
It seems that if your training is geared towards you working for yourself (e.g. freelance instructor, etc) then in theory you could set yourself up as a company and claim the vat back.
I'm becoming a little vague from here...
I think you may have to wait until you are actually functioning in some sort of self employed, revenue generating capacity before you can claim it back but there is some leeway in retrospective claims if the period is not too long.
Or if a company is paying for you to become their pilot, then i suppose they can claim VAT back to if they paid for the training.
I should point out this comes from a passing conversation i had with a financial type friend, but hope it helps