Oil light

Hi I have a freelander 1.8 petrol and the Missus just called me to say the oil light is flickering on and off while she is driving, she has checked the oil and it's almost full! I work away from home and can't get home until Friday. I can't be more descriptive as the Missus barely knows what an engine looks like never mind what is what lol. I have had a dig about on here and there is a lot of talk of oil switches? Is that where we should be looking first?
Any help would be great! Until I can get to a garage on Friday.