Got to say.... If it was me and I had someone else looking at the car that has basic capabilities, then the other disc would be done as well.

Never do only one side :duh::duh:

Your cutting corners by only changing one side & yes they can fail it for only changing one side if there is an imbalance.

I'll hazard a guess that you have used the old pads & shoes as well? :shrug:

You may have been better buying a car with a valid MOT and getting the zt repaired when you had the funds to repair it properly.

If your going to ask for advice then please at least try to take it on board.

Both sides had new brake pads fitted and i have always in past changed discs at same time, i have never before not been able to gat caliper bolts off not even on other 3 r75s but couldnt this time, tester says if all fitted and working properly should be ok and imbalance is normally on front more but i do not intend to leave other disc long

Well MOT is passed but clutch isnt very good, wouldnt go in gear and stalling but master was full so i have cut condom to act as a sealing ring and put cap back on with pipe in it then put 2 caps of brake fluid down tube and it was coming out from seal on mc lid, but clutch now feels ok again but im going to get it done in next couple o months as an investment

Sounds like more trouble ahead hopefully it lasts until you have the funds.