Then it's tough, but you have to go to someone in the NHS for treatment! And you've already had something in general outpatients which doesn't seem to have given you relief (I've no idea how qualified/experienced your physio was) you could ask around and find some specialised physio in the area you are during term time. Is there a student health center in York which could refer you somewhere? Remember also that there are physios who do alexander as well and maybe there's a loophole there for less expensive treatment, within the NHS. Answers with exercise suggestions on a web site can't replace eyes-on-hands-on-look for red and yellow flags assessment. All sorts of exercises can be appropriate for back problems. All sorts of hands on techniques can also help. Various electrotherapies could help in addition to hands on.......One size does not fit all. A physio must address the fact that you seem to have a longstanding problem, it affects your life and a physio should look at "all of you" and the chronic pain problem..not only exercises.
keep us posted, I'm sure you'll find help but you will have to ask, there must be senior physios and tutors around during a university course for physiotherapy or am I way off there??
keep us posted!