I totally agree with all the above, but...
I don't see why, as you leaving the Services and able to get grants and allowances up the ying-yang, you can't do both?
If you qualify for an engineering degree then you will almost certainly qualify for a Pt66 C Licence.
You may be able to sit in a nice office - In a shirt and tie - doing Base Maintenance Release to Service certificates, all day long!
So now you have THREE options!