first problem of the year......!

Recharged my battery today, after its been laid up in the garage after Narnia descended on my part of the world for the last fortnight!!!

Runs and ticks over nicely as always, but now, even from cold the engine fan is coming on from the minute the key is in the ignition, also the engine over heating light is illuminated from the position first - (but does extinguish). What is causing this??? Is it a sensor or relay ??? If so where is it located???