I struggled to find adult colleges that offered the A Level courses I wanted to study, especially in-person classes. I ended up studying from home with my own resources, so the fees I paid were for the exams only. Which can be very expensive. I did Classical Civilisation and Ancient History, and I'm about to take my Latin exams in May/June. Both of my previous A Levels cost me £400 and this Latin A Level will cost £500. There are adult colleges that offer A Levels but I think you might struggle to find one that offers classical civ because none of the colleges local to me offered any of the A Levels I wanted to take. As a previous response suggested you can try a HE Diploma and that will let you apply for university - some universities also offer an extra foundation year before the 3-4 years of the main degree to help 'bridge the gap'. I haven't seen how much HE Diplomas are but they might be more affordable considering the cost of exams and classes if you end up having in-person A Level Classes will likely be over £1000.