Many thanks for the replies and info.
We've done a bit more research and think we understand the lie of the land a bit better now.
It seems that B1 and B2 licencing with specific aircraft ratings is the nirvana to which she should aspire - making her employable in a wide variety of contexts (while keeping her on her tools - she's not keen (yet - give it 20 years!) on office work.
Getting an apprenticeship would be a simple and direct route in the right direction.
However, (i) most apprenticeship intakes seem to be complete for this year, (ii) they're hellishly competitive (not a bad thing), and (iii) she's weak on both academics ("A" grade GCSEs are OK but she has only maths A Level (and some irrelevant ones inc RE) - grades unknown until mid August).
So, if she wants to follow this route; she needs to do some consolidation - adding a science A Level and somehow demonstrating her practical work. Or, as she's found, doing a Level 3 Diploma (I have no idea what this is) in Aeronautical Engineering at the local college.
Specific questions:
1. Are there any "traps"; would doing too much study and too many courses make her of less interest as a potential apprentice? As hands-on work experience is so important to this career, I can imagine a degree (for example) being an actual disadvantage. Would doing a diploma at her own expense and in her "gap year" help or hinder?
2. She wants to demonstrate or document somehow, her practical skills as she has a purely academic CV right now. She's a bit stumped on how to do this so would welcome ideas. Her ideas so far are to volunteer to local organisations that might have some connection with engineering (a historical machinery museum, hovercraft museum, RNLI etc). I've told her she's more likely to end up polishing the floor but I suppose it's still CV material of sorts.
3. We're guessing that the RAF as an employer would want the same as an apprentice employer - but she's got an appointment with them soon so will find out one way or the other.
Once again, many thanks for the info.