The only current RAF FJ that will see your squawk on TCAS is the Hawk T2. The Typhoon will have a Radar to assist (the GR4 may be able to display A-A contacts but you'd best ask someone who flies it).
I see what people are saying about the large area NOTAMs but then there are civilian equivalents that are equally vague. Cross country gliding competitions spring to mind. They cover vast swathes of the countryside but in reality hardly constitute swarms of gliders from surface to infinity at all hours of the day.
What this thread has highlighted to me is how certain members of the civilian fraternity (and this works both ways before anyone jumps down my throat) don't fully understand what the military is up to and why we do what we do. Open days hosted by military units or local airfields are a great way to enlighten members of the aviation fraternity. Although at one I attended I was not overly impressed with the finger pointing attitude of some PPL types who were convinced we were all out to kill them!
BV