Basically it went bang! and steam and water started pouring into the cockpit. Luckily we were at traffic lights so just jumped out. It just overheated too much and something burst, tbh i haven't done aything to the cooling system other than topping up/cheeking coolant strength in the 5 years I've owned it! Some of the rubber parts are pretty perished and the thermostat looks like it's seized. In future I think I'll be paying a lot more attention to things that could potentially kill me! No real point to this I guess but thought I'd share, maybe other people can learn from my mistakes!