Being OTC qualified by a different route (not ETPS), and with at least one Masters, I think it is worth pursuing a post-grad piece of paper to show something for your efforts for after you leave the FT environment or the Service. An example of where the ETPS course might go has been achieved by the RAF GD Aerosystems course, which has spent some time moving towards becoming a fully accredited MSc from the same starting point as ETPS (long and not straight forward course).
There's no harm in asking decent univerities whether they can offer credits on M level courses for both FT and non-FT related studies. There are also those that offer a modular approach like JF suggests.
There is a respectable uni that offers a choice of MSc courses that are aerospace related, that are p/t and require 12 modules to be completed from a choice of over 30. I had had enough of "hard" subjects and so took my credits to get ticks in the box for the (4) hard modules and then studied 8 business-related modules.
Perhaps the FT TNA work (see other thread) will conclude that everything should be modular, TP, FTE and QAS should all be rolled together, based in one place and result in MSc?