Well i think i found (i say i i actually mean my girlfriends dad) the root of my warning light, saturday morning i went to start the car and it was completely dead wouldnt even attempt to start, me being pretty much non technically minded thought battery so stuck it on charge, 30 mins later on a boost charge still nothing, so i left it on charge and went out for the day. Got home in the evening and it fired but with warning light still on. So sunday it started so i drove it to my girlfriends, at which her dad started to poke about in the engine bay and instantly found that the earth strap was wobbling about all over the place, he tightened it up and its been fine since.
So only explaination i can think of is when they did the gear box the other week they didnt do the bolt up properly