I can't say I own one, but have driven/ridden a few road legal beasts, and I use the word beast on purpose
If they are taxed, insured and have the appropriate safety bits and lights then they can be ridden on anything, certainly up to dual carriageway. You can drive anything on dual carriageways and walk on them if you want, but can't drive tractors or walk along motorways. for example.
Not sure whether they are allowed on motorways, but certainly anything up to dual carriageway
P.S. might know someone who knows, see if I can find out.