Thanks for all the advice.
I ended up going to Keswick on Friday to pick my GF up and have a look at the car. Decided to try and limp back home (about 70 miles) at the ungodly hour of 5:30AM Sat morning to avoid getting stuck in traffic.
After about 15 miles and two stops to fill the car with water I was beginning to give up hope. Couldn't understand why the car was boiling over so I decide to feel the temp of the radiator and the hoses. COLD!!!!
Took the thermostat out, filled her up again and made it home with only one more stop to check everything was still in place and have a coffee. In the final 50 miles, the car didn't overheat, seemed to be running perfectly and didn't skip a beat. The only thing I did notice was that the heater wasn't working.
My conclusions (and quite happy to be shot down in flames) are that the water pump and the thermostat are knackered. There doesn't appear to be water circulating even with the thermostat out as the radiator didn't get more than warn and heater matrix isn't getting any hot water.
Now that we've got the car home, we've decided to let the professionals have a look at it. It's worth an hours labour to get their opinion so I can decide if I'm going to attempt the work myself. And with all your advice, I'm a lot happier to have a go and save myself a bob or two.
BIG thanks to STW