Edit/clarification: I forgot about British multiculturalism. You would have to imagine Britain had similar 'national and ethnic trauma' to Israel for first IRA example to really work.
The IRA's goal was to unite Northern Ireland with the rest of Ireland. That goal, while not as hard to attain as the right of return, was still unacceptable to the UK. The IRA achieved some of its goals, and clearly decided to bide their time in peace. The Palestinians could hope for the same sort of partial victory, with a negotiated peace with the Israelis.