Don't do it mate! A decent quad will set you back a few grand. Get a 4x4 instead. Quads are great as an addition to but not instead of a conventional motor. No weather protection, no passengers (legally) insurance is expensive if it's used for commuting. No room for much stuff on it and very little security for what you can carry.
Tax is about £115 for mine, insurance £250 (1000 miles per year max) and you will also need helmet and leathers etc if you are seriously gonna use it as your sole transport.
Sorry for the reality check mate but use your head not your heart. Cheers, D
yo