ok so I managed to seal the hole up by cleaning the area and peeling back the rubber coating, I used a 2 pence and some gasket sealer which worked, i used some coma 75/90 from Halfords and it took about 500ml to get it back upto the full level.
problem i have now is i can hear a knocking noise in the gearbox when the car is parked up. not sure if this noise was here before or not. there isn't any patern to the noise.
1. not using gearbox oil from TPS causing the noise
2. try shim mod if not already done
3. gear box is knackered.