I managed to get 8 flights in Hawks at Valley with 208 and 74 squadron in 1998, however I was a member of the RAFVR (University Air Squadron) I have to say that you have no chance of getting a trip, especially with the current shortage of mil flight hours.
It was an awesome experience, but at the same time bloody exhausting and bloody unpleasant after about 10 minutes sitting as a passenger in the back seat (sustained +5G is not a nice experience). The nausea was unbelievably intense and by my last flight I felt so ill that I vowed that was that for fast jets. Got some awesome photos though!!
Have you ever thought of getting a flight in a SU26 or Extra 300? Now that is fun!! Much cheaper too!!