If car is stationary and idling the temperature gauge stays at 50% and the heaters blow warm air as they should, but when im driving along the gauge goes down to 0% and the heater blows cold air(even though on full/hot). Getting to be a pain as its not the warmest time of year, and i hate being bloody cold

 

sounds like thermostat stuck open to me

 

where would a thermostat be when it's at home

 

follow the hose from the radiator to bottom of block next to crank pulley,you will need to get underneath to see it.
iirc it is held on by 2 10mm head bolts

 

how would i make it not stick open

 

Check your water level, no water = cold heaters
no water = no temp reading
If your water pump is not driven by the cambelt, tighten the belt that does drive it

 

by changing it for a new one

 

i'll give the new thermostat idea a whirl if that doesn't sort it, i'll try and find the water pump, should be fun as yet again i aint got a clue, lets hope the thermostat is successful