Hi i have a fabia vrs mk1, driving around town the other day after being stood for 4 days and decided to cut out and since has developed excessive cranking over till fireing up any ideas? Maybe crank position sensor? 

Check your glowplugs, colder weather means more glowplug usage, also the ECT sensor may be tired.

Sorry forgot to say starts fine when cold, once warm struggles to fire 

Sound like some kind of sensor I don't know to much about what it could be, possibly MAF - are you able to do a scan for faults as it may tell you ?

crank sensors are more likely to fail hot but work again(for a while) when cold

I seem to think it might be the crank sensor as its happened to another car i had similar issue... Where is the sensor located?

Any idea where the crankshaft sensor is