Possible option for trials experience is what was Air Fleet Dept (AFD) of what is now QinetiQ at Boscombe Down. Ask about their student/grad opps. Years ago I had fun getting involved (in a minor "what can we trust to a new graduate" way) working on initial UOR94 TIALD/HMSS/Digimap/GPWS etc. Jaguar mods (that later turned into Jag 96, 97, GR1B?, GR3 etc.) that AFD were involved in. Also got involved with Sea King, Harrier T10, BAC 1-11, Canberra and 748 mods. Great experience for an engineer - not sure whats left of the fleet though these days (is TIARA there now?), but bound to be much more varied experience than an RAF station and many more varied/broad scope engineers (rather than just maintainer related engineers) to interact with.
(Sorry ABIW just read your last post - I won't delete in case any others may be interested..)