Not true, I was a mechanic before I went on my Tech course, I was involved in all the engineering both on fast jets, well fastish (Jaguars), helicopters and also VC10's........
I did exactly the same work and only did a short period of just flight line work on it's own (couple of months) in the RAF, I even spent 6 months Deep Strip and Overhaul on the Adour (the low point in my career), I do not believe these days can afford not to diversify their engineering skills due to the lack of manpower...........
Enjoy it mate, I did, I spent 15+ years in the RAF and it gave me the grounding and skills to take my licences when I left the RAF... I would work towards them when you are in as well, mind you I was told that as well and didn't.......... ahh the fun of youth......
If I can think of anything online to help you, I will post it, I am a torn between giving you civilian links as they do not totally follow the Military format.