where abouts is the power steering resevoir on the fabia vrs? noticed recently that my steering is heavier then usual but not all the time? sometimes it feels ok?

Resivour is under the battery IIRC - awesome idea Skoda!

Might be the sensor if it's only an intermittant fault - search should show it's a common issue.

is it easy to sort?

No idea, I had the whole rack go (was leaking) rather than the sensor (if that is the issue) - hopefully someone else'll be along soon!

Sensor is easy to replace, but to check fluid it's a battery and tray out job, and to get the tray out you need to move the airbox back as well.