I'll chuck my twopenneth in! I'm a PAraglider pilot - hill launch oversized kite. I can't talk for the sailplane fraternity, but I can offer a few pointers from our lot. The majority of soaring sites are marked on airmaps, some aren't however & that can be a problem. If we fly around military areas, Wales, Peaks etc, we NOTAM the freephone RAF no during the week. The vast majority of hang & paraglider pilots will fly belwo 1000 agl all day, in any event, no one will be above cloudbase, except in rare wave conditions & then only the brave!
Long xc's are commonplace - 100ks regularly gets flown from my home sites & pilots will be anywhere from 50agl to cloudbase on those days, but they will be downwind of the hill they began from, so possibly worth bearing in mind. The xc season in the UK runs from spring to autumn & the classic days I.e. those likely to bring you into contention are post frontal light northerlys, high lapse rates, plenty of instability & cumulus clouds - them's the signs.
Having said all that, the vast majority of pilots are punters (like me) who do not want to bring down the wrath of the CAA on their heads & follow all the rules - it just takes a couple of morons to ruin it for us - currently, the CAA are making noises about compulsory xponders for us lot, following an airprox near bournemouth airport - we don't want them, so most of us behave. I spose we're a cross section of people like you'd find anywhere. Hope that helps.