In reply to EvaP:
Hi Eva,
Happy Trails: I'm sure you'll have a ball! I'm afraid I don't have any direct experience (and I'm more keyed into the Appalachian Trail, which I did many years ago, and I've been on AT trail crew more recently). If you haven't already, I suggest you might want to look at ALDHA (http://www.aldhawest.org/) and the PCT Ass (https://www.pcta.org/) both of which are quite active. Not exactly UK focused, but might help, or someone may know someone who's over here in the UK.
Speaking of Trail crew, both the Appalachian Trail and the PCTA run seasonal volunteer trail maintenance crews. Depending on your time and budget, they might be worth a look. When I've been on the AT Trail crews (which I've done for quite a number of years, but have had a break recently), there have always been quite a few volunteers who have volunteered on crew as a way of getting into the trail community and scene and information with a view to doing a thru-hike in a year or so. I can't speak for the PCTA crews (as I've only heard about them second hand) but the AT ones are generally quite good and fun: they feed and house (tent) you in return for toil and sweat, but it's a wonderful bunch of people: see http://appalachiantrail.org/crews
HTH