I agree with the OP that gliding is one of the best ways to get into Aviation, so much so that CTC has been endorsing it alongside the British Gliding Association with 16-18 year olds learning in the UK who should then go on to have a fantastic CV.
As the OP is in Europe I assume, Minden is of little value. Instead I'd recommend Lasham Gliding in the UK, the largest club in the world open 364 days a year. Courses throughout the summer. Since instructing for Lasham I have flown with everyone from retired training captains to aspiring ATPL applicants.
All agree that gliding is a fantastic way to get some proper flying skills for little cost. And if you're good, you could build hours flying the towplane for free!
Ultimately this is your investment, clearly you have hit a hurdle but you now need to be really sure that your aptitude is good enough to recommence ATPL training. Everyone learns at different paces, but there is only so much money you can throw at it.