Experimental have to have permission from the authority of every country they overfly or come to so my guess is that it would be difficult to use it in the UK. But a one time permission to come to an event like an airshow could be a chance.
Fixed wing aircraft are operated privately all the time beyond the TBO limits of the manufacturer and one hears about operators in certain southerly hemisphere continent who have operated the R-22 well beyond the TBO limits set by the manufacturer so if the aircraft has special maintenance and is taken extra good care of it should be able to be used further expecially if you are talking about the calendar time limits which are mostly there to make more business for the manufacturer.