decided to seek help from Apple Support as you suggested. After a long telephone conversation, and trying numerous things, we managed to resolve problem by switching of wifi router and performing reset on iPad, then switching on router, and reconnecting iPad to wifi. Support guy said this resent IP address. Interestingly, my husband has had same problem on his iPad ( he doesn't use much for Internet browsing, so hadn't realised his iPad had same problem. Solution worked for him also. However, it has recurred, so not sure if this means I have a problem with my router, or broadband provider. So at the moment I can get limited solution, but need to try to find out where the problem originates!
thanks for your help with this.