Overheating?

[k3ogh]

Ok so my daily traffic basher is overheating erratically it will get up to normal running temperature and then go up past 90 etc and then go right down to 70 at random, I'm thinking thermostat or coolant temp sender? It also blows hot and cold on the heater depending on the coolant temp.....

Really need a cheap fix as I do 1k miles a month in it for work, I can't see it being the head gasket as I done that not long back, anyone experienced this?

Cheers chris