Thanks fellas - you're very kind. So many stories of true inspiration on the www of people who've been through much the same. Taking it easy at the moment, walking a few reps of 200m or so each day is the first target and I feel ok.
To answer Paul's question re hereditary/lifestyle thing in all honesty it's hard to say. Sure I've burnt the candle at both ends at times but I've never smoked, always been reasonably fit although slightly over-weight at times too. I do suffer from shocking levels of stress/anxiety though which has made me physically sick, periods of which have gone on for months - it doesn't take much to trigger. According to the BHF the case for a link between this and circulatory problems is getting stronger by the day.