Head gasket + cambelt + waterpump - £325 to fix. Cheaper than replacing a cambelt on most motors.
I have found my MG to be super reliable, cant fault it for the money you buy em for. I think the reputation they have with some people is unfair.
Mention an MG or Rover and people go 'ooh head gasket' like its the end of the world but if you get it fixed and uprated and then keep an eye on your levels as you should with any car then it wont happen again!