Semantics maybe, so apologies in advance. But to be a flight test engineer I thought one had to attend one of the TP schools in that capacity. I was always very careful to describe myself if asked as an FTO (flight test observer). There was an ocean of capability between me and our FTE; the ETPS FTE course made a very impressive product indeed.
I'd suggest that a job with QinetiQ in a flight test capacity should place you well to get on the FTE course.