I had better add what the problem was! Just in case anyone else has the same!
Not long ago I was out and about and the oil warning light came on, followed by the buzzer (this was only a few miles after an oil and filter change), I was only round the corner from home so quickly pulled in and checked levels etc not knowing it was pressure related (at the time), anyway, cut a long story short and with lots of help from James Butler over the phone I ordered both pressure switches off ebay, figuring I may as well have both new instead of one, fitted them and off I went, only for it to happen again! Phoned round every single garage in my area inquiring if they have an oil pressure test kit, out of all, only one did, and he was too busy to see me this century anyway (it was a week really!) so I bought my own and tested it, 2.5 bar at 2k revs, all good! (phew!), problem however still remained. In the end I washed out the old "genuine VW" switch in petrol and put that back in, so far, no drama, no buzzer and no light!
Just for future reference I got the switches from here http://www.ebay.co.uk/itm/200998235893
, not saying they are all going to be duff, bought other stuff from there and its been fine, could have just been a one off etc but theres something to be said for genuine vs third party!