I currently fly power and gliders at a smaller club a bit further north,
Portmoak has superb instructors, a good fleet and is in a decent place to learn to fly.
Every airfield has a doom and gloom merchant on it, practice see and avoid skills early
Unless intending to go the full CPL route, you'll get tired of spamcans and 100 quid bacon rolls quickly, Gliding never gets dull.
The day the guys were referring to Ed banged out over 1000km, John W (Scottish one) did 900+ km at over 150kph, with no engine, Sant did the highest scoring flight in the UK from Portmoak (lower performance glider, higher scores)
Costs, like any form of aviation, you can spend what you want to.
Flying the club fleet will keep costs to bare minimum, club membership then as much or as little as you want to spend a month from there.
Gliders cost from 500 quid for a share in a multi person syndicate with a vintage glider to 450k gbp for a nice self launcher, and anywhere in between depending on your wants and desires.
'tis challenging and fun, avoid the club politics . . . .