Just in case the boat is not UK registered: The important / complex thing is making sure you get a clear title, no loans or unpaid bills on the boat, and possibly de-registering. Registering is then typically a piece of cake (in
germany it's just one form to fill plus some certified copies of your documents).
A UK solicitor may not be very knowledgeable when dealing with for example the italian authorities. Worst case you end up paying for a boat and don't get a clear title.
So find a solicitor that actually lives in the country of registration. Plenty of UK folks have settled around the
Med and other nice cruising areas so that should not be a big deal.