Zooker's correct. In the UK FIR you'd be expected to continue along your flight planned route as per your original (on ground) clearance unless it's been amended while you were in the air.
Most of the time you will be given (and should receive) an ongong route, but failing that, keep doin' as you're doin'!
The same follows for radio-fail purposes. PLEASE slap on a 7600, then continue on your flight planned route - that's what we'd expect (as well as 'anything')