The sets used for 4x4 response and for SLROC events are VMH sets and you need to get a club to agree you can get a licence. The RAC hold the master licence and allocate clubs with call signs. eg SLROC members that have a licence via the club are all "LOWBOX" call signs. Some members have a different call sign if they are also in another group and they allocated the callsign.
Cheers Andy Norrie GM1MQE, Lowbox 7, and Highbox Control
Last I checked these can only be used on MSA authorised events?
For GRRs as everyone says CB is the most popular, however there are more and more people getting their amateur licences for UHF/VHF.
Coming from a PMR background I'd have to advise against using PMR sets, more hassle than their worth unless you're operating in a group and the same people are using it.
PMR 446 stuff is ok to use as it's licence free, however you require PMR446 approved sets as they have to conform to certain standards.
Any questions give me a shout.
Navigator, if you need a hand give me a shout.
Thomas
MM6LRS
LOWBOX 42