Lots of great advice, especially the one about getting a Class 1 medical. No, you don't have to go to an AME, you can look up the requirements online and ask your family doctor and optician to check things out.
Don't ignore the couple of elephants in the room, namely the environmentalists and the single pilot flight deck. Given the huge surge in demand as soon as the borders opened up, maybe that one will fade and also, there are a lot of smart engineers and chemists out there. Coupled with the possibility of short haul e-props, the future may be ok. As for the single pilot flight deck? It's coming. Just not exactly sure when but there are several serious projects under way. The UK ergonomics society put out a white paper about it in 2020. Worth a
read.
I just spend a fun 6 days flying with a former BA pilot. We were chatting about the industry (naturally) and agreed that our sector (business jet ops) was probably the most interesting in commercial aviation.
We did run a cadet scheme in the past and may do so again in the future (no one knows). However, this side of commercial aviation is expanding rapidly. Much to Greta Thunberg's annoyance.
Definitely get some life exposure before signing up for a full time course, especially if it's a "tagged" scheme that leads straight to an airline job. You'll need something to talk about in the cruise. The advice about getting some skills in computing or a trade is very sound. You can always get a degree later (that's what I did).
As for the UK v EASA licence? There's a lot more jobs in EASA land than the UK. If you can, get both.