Drain the whole system imo, bottom hose off the rad, hose off the thermoustat housing, let it all drain oot and start from scratch.

Makesure the fan is going the right way, and when re-filling take the hose off the top of the thermoustat housing, the thin one and the air will escape that way.
when it's nearing fullness. . start the car up, level might drop a little so top up to max, leave cap off till it starts to get warm (oh and watch for water coming out the thermoustat housing where you took the hose off) put the cap back on, and wait for the fan to come on.

if that doesnt help then go to your local newsagents, buy pack of matches and 1 bottle of lighter fluid

Is the thermoustat fitted the correct way round?