VW Lupo help please?

I have a Lupo diesel and recently had the keys stolen while playing football. I now use the wife's spare but the cost of a replacement key nearly gave me a heart attack. My question is, can I immobilise the immobiliser, i.e. just have a key cut that will work without having a chip in it. The car is ten years old so it's not at high risk of being stolen and anyway I would prefer not to have the immobiliser in use. If you can help I would be obliged very much thankyou.

Kind regards, Frederick.