A Level Resits

Can anybody help with my situation,
I’m resitting three A-levels (History, Business, and Economics) and planning to sit them privately. I won’t be attending a sixth form, just sitting the exams at a school as a private candidate. I’m trying to figure out the best way to get feedback on my work, since tuition fees are really expensive. Are there any online tutors or even YouTube tutors who give marking and guidance? I was also thinking about asking the school if they could mark past papers once a week or every other week (obviously it would cost but surely it would be cheaper as I’m paying to do exams with them too). The only thing I’m unsure about is whether it would be a problem if the school uses a different exam board, it may complicate marking or wont allow me to get it marked completely. Has anyone done something similar, and if so, was it expensive?
Any advice would be appreciated.