Just to make you guys feel better, mine has just sailed through the MOT for the second year i've had her, with no prep work being done both years
Had plenty of other problems with her lately though
We've all had moments with our S1's when we just wanna say fuck it ! Thing is with the problem you have, it could be a number of things. it's a process of elimination Mine turned out to be the distributor the first time it was playing up, then the plugs the second time that had only been in a couple of hundred miles
Hope you get sorted fella especially now the summer's coming