Excellent information, everybody, and thank you all again.
It seems my understanding was frighteningly limited, so thanks for the patience shown in going through the process for me.
I clearly have a lot of thinking to do and a lot of questions to ask the instructors during the PPL in May (doing ground study from books at home in Barcelona now and then the exams and practical during 2 x 2-week stints in Jerez [south-west Spain] in May).
Perhaps I should have tried Cranwell instead of going to Sandhurst! School and uni were much more army- than RAF-focused, and it's strange how these things can guide one's life!
Thanks again.