As you admit you have health problems I would certainly not consider Line Maintenance. Working 12 hour night shifts requires stamina and decent fitness levels (as well as an understanding family!)
Although your age shouldn't be a barrier to entry, in reality it probably will be if you are considering a career as a licensed engineer. To qualify you are looking at five years of hands on experience plus a lot of studying and exams. You may be able to shorten that slightly by attending a JAR147 training facility but no operator is going to give you full certification privileges until you have a decent amount of experience with "live" aircraft. You will also need to study further for type ratings before gaining any full type approval.
Its a long slog and starting from scratch at your age is something I've never seen in my 30+ year career. If you do choose the Degree route, you may get an office job in a Tech Services, Design or Planning role but opportunities are fairly limited. Either way, a Degree is not the way to go if you are considering the Licenced Engineer role.