AFAIK the SSR is not transferable, the previous owner would cancel it (if it was registered) & you would re-register.
Good info here
VHF, there are 2 VHF licences, an Operators licence, which is your individual licence. Then there is a Ships licence which lists all the radio equipment on the boat, VHF, Radar, PLB/EPIRB, AIS, SART etc. This must be surrendered when you sell the boat. You can apply for a Ships VHF licence on line at
OFCOM & it's free