UK Bike options for a foreign road tripper

Hello chaps, I'm an American planning a season long (3-4 months) Euro grand tour for 2027, and I'm trying to choose between renting and purchasing a bike for the trip.

Does anyone know where I can learn about regulations regarding buying, registering and insuring a bike in the UK as a non-citizen? The plan is to start at the IOM TT, then ride south through the continent and return to the UK by September for the Goodwood revival. Thanks