Ofcom is the regulator for over the air broadcasts in the UK. An Ofcom Community Radio Licence gives a radio station the right to provide community radio AM or FM broadcasts in a particular area.
However, the Ofcom licence does not grant the rights to broadcast PPL or PRS for Music repertoire. PPL and PRS for Music control copyright in their respective repertoire and so a licence is required if music within the repertoire is broadcast by your community radio station.