There are lots of Mil aircraft showing up on FR24.
Yesterday there was a RAF Sentinal doing the most accurate race track patterns I've ever seen, over the north east coast. There are plenty of F15's, Typhoons and GR4's showing up. Keep an eye for them coming out of Conningsby, Lakenheath, Marham, etc.
They seem to show up as a certain type of aircraft icon on there. Small stubby twin engine icon.