Is London Gliding Club the type of club where you'd have to spend all day at in order to get any kind of flight?
I fly at LGC, so would say “no”. We cater for a fairly broad church, so you *can* spend all day there involved in the operation if you want to, but it’s not compulsory. To be fair, most of the big clubs have gone this way as it’s not the 1960’s any more.
If you want to fly at one of the busier sites, it will be more expensive, simply because they have higher overheads due to having to employ professional staff to run a 365 day a year operation, plus keeping a fleet of training/solo aircraft in good flying nick adds significantly to the financial burden. If you want minimum expenditure, somewhere out in the sticks can provide super value but only if you have lots of time to spare and are prepared to be disappointed when you turn up and the winch driver / instructor / tug pilot / glider doesn’t. Even at the big clubs, a lot of services are provided by keen people giving of their time and expertise for nothing.