Just for information.
I've just replaced the belt and it has reduced the noise quite a bit.
I think it will be fine without a shock.
I can now hear 3 distinct noises, the loudest sounding like a hydraulic lifter, it goes away at high revs. The other is from the chain. I have bought a chain tensioner so I'll fit that soon.
There is also a slight noise from the downpipe/cat area so I'll check that out.

I have also noticed my fan doesnt seem to come on so that needs checking(hopefuly the sender unit), and I have just broken the head of one of the thermostat housing bolts!

I think the car will keep me busy for a while yet!