where is , and how easy is it to fit my own lambda sensor on my car?

I dont know how good the access is on this car, but generally speaking, if you can change a spark plug you can change a Lambda sensor.
In theory you just unplug the electrical connector, unscrew the old sensor, screw in the new one and re-connect the plug.
On some cars you will have to jack the car up to get at it , DO NOT GO UNDER THE CAR WITHOUT PUTTING IT ON STANDS!! Never trust the jack, it's a mistake you only get to make once.
You may need a special socket or spanner like these -

http://www.fast-tools.co.uk/acatalog/Exhaust_Lambda_Sensor.html

http://www.tools-n-all.co.uk/Laser-4257-Lambda-Socket-Spanner-Wrench-Hex-Tool?CAWELAID=154256841

Make sure you get the right size, usually 22mm but not always.

Get some general info here -

http://www.lambdapower.co.uk/technotes/fitting_guide.asp

Depending on the year/model there may be two sensors, one before the cat and one after it, make sure you change the correct one!
If you plan to work on the car yourself it may be worth buying the relevant Haynes manual, £20 from bookshops, amazon, Halfords etc.
It might be worth looking for

"skoda forums"

on google for specific info.

laguna
November 2009