Go for it. Best job in the world. apply to Nats first though. Generally work 6 on 4 off at 24 hour units, typically two each of 07/1400, 14/2200, 22/0700.
Depends where you work as to how busy, but I think at Manch they are not particulary busy through the night, will be corrected if I'm wrong though. Expect to be busiest around 5am to 8 ish, then drops off til about midday, then an evening rush.
Radar heading is a heading assigned by a controller, taking the aircraft off its own navigation. Usually given to ensure/achieve separation, and, in Approach to vector for the instrument approach for the runway.