swap bikes
ride with a group of roadies for a few months, won’t improve you technicaly, but re-sets your fear switch to that of a 12 year old (i.e. you forget that crashing hurts).
get a BMX, best £250-£300 you’ll spend, nothing teaches pumping like a bmx, 26″ wheels, slack angles and seats are just tallent compensating clown bikes in comparrison. 90% (well lots of) of BMX jumps are designed as step-ups ( i’e’ they look intimidating, but if you come up short your actualy barely moving by the time you hit the landing. Transfering skill to a BMX is a lot harder than going the other way round, so dont be tempted to short cut and try to learn skills on a mtb you realy should be pickign up on the BMX.
3 steps:
1 get rid of the fear
2 start small and build up, just because you cant land a 20ft double doesnt mean learningt he propper technique on a 3ft pump-lump is beyond you.
3, variety (this is where havign lots of different bikes helps), dont get obbsessed with clearing one big gap. Otherwise failiure will demoralise you. Practice cornering, jumps, gaps, climbs, rock gardens, bmx, trails, etc etc etc etc