I feel that you would have no chance in getting a seat in any fast jet, unless it was in civilian operation.
The RAF and USAF are not airlines and will not allow the public to fly in the back of anything. The only way you can get to do it is if you are in the RAF and get a 'jolly' for hard work or a TV presenter, and thus bringing good
PR to the RAF.
I spend many years with Tornado GR1s and 4s and the only person we ever took up that wasnt in the RAF was Juan Pablo Montoya, and Mclaren still had to pay for it!