Mmmmm.... interesting ...
Most(?) countries would allow training for professional qualifications as an "education expense" .... having said that you (probably) cannot claim training to PPL level which is usually considered a hobby ....BUT once you have a PPL you should be able to claim further training (CPL ATPL) to "professional qualifications" as a valid educational deduction. You might not be able to claim the total spent (perhaps a percentage depending on your tax rate??).
Talk to the "Tax Man" try to get a "personal ruling" or whatever that may be called in UK .........
Good luck!