Hello grovesy91 & welcome to the world of trials. Warning though it’s somewhat addictive !
The first advice I’d give a newcomer is to go to a local trial where there’s a beginners/easy course running, and have a look at what the sections are like. Get there in good time & talk to as many people as you can before the start. They are on the whole a friendly bunch , & will all be standing around nattering half an hour before start time anyway and you might pick up some good local info, maybe you’ll find some secondhand gear for sale or even a bike !
Secondly about the bike. Your budget should get you a tidy machine to start out on. 125cc would be ok but need more revving, 250 is probably better (and 125’s tend to have been revved by junior riders), bigger than that might be a handful, but don’t rule anything out, they’re all ok. Anything around 2003 onwards is plenty competitive enough (beta rev 3, Sherco, gas gas pro, etc) and although newer is generally an improvement it won’t make too much difference at beginner level. Don’t know what your mechanic skills are like, but look for something well looked after. That usually means it will look clean for starters, then check basics like chain & sprockets, wheel bearings, rims for straight & true without spokes bent/missing, steering head bearings, tyre condition, and general condition of plastics & painted parts for signs of hard use. Bearings are generally just a few quid to replace, a pair of tyres will add 160 to your costs, plastics can be astronomically expensive so check they’re in one piece. Well looked after bikes might have some scratches & some stickers missing etc from the nature of the game, but will be fully functional, with any wearing parts replaced as required.
Thirdly, once you get a steed, get out and ride it ! Even if you can’t get to some proper off road area just practice figure of 8’s on the garden/drive at low speed & full lock, then you can throw in maybe a length of timber / breeze block / or even a ladder to ride across or over. It all helps.
Then go out & try a trial, don’t put off the competition element because that really is the best way to learn & improve. You’ll get lots of help & encouragement from other riders.
Finally just be aware that there are thieves out there who like off road bikes, so keep it locked & if possible don’t advertise its existence to all who pass by your house or storage place.
Good luck and above all enjoy it. It’s great fun, good social, and a surprisingly good workout.
