Thanks everyone for all the thoughts, advice and condolences... As someone has already said hindsight is a wonderful thing. Nobody thinks it's going to happen to them. I debated when I got the car about doing the IMS fix but took a gamble which didn't pay off. If I had to do it all over again I would probably do the same thing. Nobody has been able to tell me why it happens, when it happens, how many miles it happens at or even if it's going to happen... I thought after 77,000 miles that I would be safe enough because I had read that it normally happens before then (if it's going to happen at all).
I spoke to my mechanic this morning and in his experience he believes it is the IMS but won't be able to tell how much damage until he sees it. He suggests it's probably an engine replacement and has quoted me around £600 for the labour. I've been able to source a second hand engine for £2,400 (2.7, 61,000 miles) from my local scrap yard which seems to be pretty good value compared to what I can find online (£3,500 from my first online quote).
For those of you with helpful advice thank you very much for your input...
