If you go to
http://webwise.bt.com/webwise/index.html It tells you if it's switched on or not or as in my case that it's not available in my area.
They very craftily tie it up with a so called security feature
BT Webwise helps to increase your protection against online fraud and make your Internet browsing more relevant.
BT Webwise automatically increases your protection against online fraud by checking against a list of known fraudulent and untrustworthy websites. When you visit any website on the list, you'll receive a warning, so you can choose whether or not to visit it. It's another way BT is helping to protect you online.
BT Webwise also personalises the online advertising you see on participating websites by linking it to your interests. For example, if you search for a weekend trip to Paris or visit pages related to Paris, BT Webwise would help provide relevant advertising for travel or hotel information. You won't see pop ups. You won't see any more adverts than you normally do — they'll just be more relevant!