I decided to go ahead with the welding and now have 12 months MOT, but £300 lighter!
In respect of the clutch the mechanic said it could last for a while and might be worth waiting. I have driven it with a high bite for a good few months and it only slips in 4/5th gear.
What is the best way to nurse a clutch? At the moment I accelerate very gently and if going up hills use lower gears.