The Academic route is this:
You must achieve a degree qualification acceptable to the NAA plus
1 year of practicle experience on the shop floor working through "a good selection" of ATA chapters/subjects plus
A full Part 147 type rating course for the first type of your approvals. A familiarisation course for second and subsequent types on your approvals.
Following all these things you can then apply for (but in UK not necesarily achieve) a C Licence.
You are right is saying that you can then sign-off a base maintenance check - that is entirely what it is designed for. It is designed to be used with a Project management/Quality Auditor who asseses all the work carried out and checks for the compliance with the package of work - nothing else.
I've always looked upon it as a management tool to get around some commercial pressures, but who am I in this great machine!