I administer the Cranfield course at another University, so what I'm about to say has to be viewed from that perspective.
First, the Cranfield team are excellent. Extremely knowledgeable, highly experienced, very friendly. Having said that they work bloody hard when they come to me (our students do the course from Glasgow Airport). My students get 2 hours' worth of ground school per day for 3 days. This means that they only get to speak to the test pilot on the 4th day for the end-of-course debrief. Cranfield have in the past flown up to 6 sorties per day, so the crew are really too busy to speak to the students preflight, and even post-flight and I discourage my students from doing so. One or two of them will go up front but I've never known the Cranfield guys to send them away 'cos they're too busy.
Second, what you actually do is a function of your University - I may stand to be corrected but I believe my institution is the only one to do what might be called the 'full' course - pressure error corrections; lift, drag and performance; static stability and certification; dynamic stability (modes of motion). Within that we do have an Avionics demo, usually GPS/ILS comparisons on the way back in. Other institutions do various subsets of the full course. My students then have a degree examination in which they'll have to answer questions based on the flight test course - I'm even able to frame a parameter estimation problem based on the flight test data from the modes of motion demo, even although Cranfield don't do parameter estimation with the students (parameter estimation is a black art that allows extraction of stability and control derivatives from flight test).
Third, they're on the first season with the new aeroplane, so not everything might work! Serviceability seemed pretty good when they came to us in March.
Finally, I would encourage you strongly to seek them out and ask questions - just pick your moment. They want you to get the absolute maximum out of the course, and your institution will have spent a lot of money so I'm sure that they would much rather you were active rather than passive.
Oh - the most important thing. Enjoy!