A/g + Fiso
To the best of my knowledge, all you need for A/G is an R/T license and the permission of whosever radio it is to use it.
There is CAP (the number escapes me -is it CAP413? -but it is downloadable off the CAA website) detailing the syllabus for FISO exams. There are a couple of types. One for Area (FIR etc) and one for Aerodrome, with slightly differing requirements.
Details of exams and costs are usually disseminated through WHITE AICs (available from ais.org.uk. Look for the AIP)
Regards Mirach