The Tornado F3 the RAF flies is similar in its top speed to the F-15, F-16 or F-18 here in the U.S., which can do 2.05 Mach or so. However, since they don't like to break the sound barrier over or near populated areas, they usually patrol or practice at around 500 MPH... at least in most areas of the U/S/. with the exception of Military Operation Areas (MOA's) in the deserts of western U.S.
While at an airshow at Folkestone Kent a few years ago , there was a flypast and display by Tornado's . They were down from their base in Scotland and as they left the commentator said they would be back at base having a pint (or cup of tea ) in about 45-50 Mins.
So along the south coast reckon about that , give or take .