I looked into this (before the price went up) and then moved to doing a Masters the usual way.
As I remember OU degree courses can often be built up from linked modules. So a starting point may be to do a broad module in humanities/social science which could then count towards a really wide range of degrees – quite possibly law – you will have to check. This way you could see if you enjoy the learning style of OU and the sort of stuff covered and get back into the academic way of thinking (and writing)
I am doing an MA in political economy full time at a traditional Uni, my undergraduate degree was a BEng in Metallurgy and Materials Science, and I am an accountant by profession, so I think chopping and changing is possible Am really enjoying my course but it isn’t easy by any means there is whole world of new jargon in social and political science you don’t come across in the real world!
Obviously I don’t know the nature of you illness, but could you consider doing law through a standard uni – perhaps part time? I do like having the structure of seminars, face time with fellow students and there are lots of extra curricular lectures from political groups, visiting academics etc which helps broaden the subject.