The UK issue a Flight Radio Telephony Operator's Licence FRTOL to any person who qualifies for the issue. There is no requirement to complete a formal course of training though this might be adviseable. The test can be taken with any of the Examiners listed in this
document. Prices vary, some provide training as well as testing. Your friend will need his passport to identify himself and he will need to be able to speak English to at least ICAO Level 4.
Details of the examination are
here
The privileges of the licence are in Schedule 7 of the
ANO and essentially only allow the holder to operrate an aircraft radio station in a G reg aircraft. They do not include ground radio operation and it is not a licence for a radio station.
The cost is given in this
document:
for the grant or renewal of a Flight Radiotelephony Operator’s Licence (except where the applicant is the holder of a licence to act as pilot, flight navigator or flight engineer), a charge of £70.
It is freee to the holder of another UK Flight Crew Licence.
There is no such thing as a JAA radio licence. Each JAA State may set its own requirements to comply with International Telecommunications Union (ITU) requirements