license
Try and get a job with a company doing base maintenance, I see your at broughton so the nearest potential employers would be Monarch or mytravel at MAN.
They do advertise every now and again for mechanical fitters and they will take your experience into account.
As for the module exams, you can take the exams at any time, while you're studying at college for your apprenticeship have a look at the maths and physics modules they are not that tricky.
Come the end of your apprenticeship if you have 4-5 modules under your belt it will look better to any potential maintenance employer.
The trickier bit is proving experience. Along with the modules you will need to prove at least 3 years maintenance experience (5 years if they dont recognise your apprentice training as relevant).
I have had to followed the same path i.e going from production to maintenance, I had to move to glasgow to get a position as a mechanic 3 years ago and have recently finished my last module and got enough experience under my belt, so it can be done!!
hope this helps