Iphone 4S Wifi Greyed out and Battery Drain

I've had my Iphone 4S for nearly a year now and I updated it onto IOS 6.0 back in september. It was working completley fine up to now. The battery runs out very quickly too (only lasts about 3 hours after full charge). I realised this is a common problem but is there any way to fix it without replacing because I don't have a warranty. I live in the UK btw. Many Thanks.