Run the engine for a couple of minutes to warm it up and get the thermostat open. Turn it off. Disconnect the top radiator hose where it goes into the radiator and start the engine for about 30 seconds. Does water flow out and keep coming out? If yes then the waterpump is working ok and you don't have any blockages. Problem is the fans.

Can you turn the fans by hand - blades aren't getting caught on anything?

Do what George suggested above, do the fans now work?

Cheers

Paul