Having an RT licence is the only requirement that I am aware of to be an A/G operator. The CAA will validate your own licence once you recieve it for your PPL. Being a pilot on the other end of the transmition will give you the advantage in knowing what to expect on the RT. Having been flying for 20 years now, the transition into A/G was very easy 8 months ago when the opportunity arose for me. I am sure that there are plenty of small airfields out there who would be only too glad to have an extra pair of hands on board ( especially at weekends). Make a few phone calls, offer your services FOC to start off with. Above all ENJOY your flying.
Noelwj