No, term limits aren't really a thing in the UK for elected officials in general and the longest-serving MPs today have been there since the early '80s. Even Prime Ministers can stay in their position for as long as they have the support of their party and can command the confidence of the House of Commons which in some cases will be for over a decade, although it's normal practice in the UK for a governing party to change their leader and therefore the Prime Minister mid term.
Some appointed positions have term limits (some 'machinery of government' kind of functions, some quangos and public bodies etc) but a few are for life or retirement such as members of the House of Lords.
