The heating in my car wasn't working checked the water level and realised there was no water in, it's now at it's correct level... any idea's what may be wrong?
Could be leaking from the following - radiator, heater matrix, various pipes, head gasket, water pump.
If there is a leak have a look for white salt deposits that usually get left where it is leaking.
I've checked the level this morning it's dropped about an inch below the max mark, so I've topped it up again.
There's no visual evidence of a leak... but I do have heat
Oh dear........you may have a blown head gasket.
Are you blowing clouds of steam out of the exhaust? If there's no external sign of a leak then the water may be getting into the combustion chamber. Keep your fingers crossed.