It really depends on what your long term plan is. If you just want to upgrade your home, then do it - no time like the present. Don't forget the new property will rise in value too.

Although alot of people get a valuation and think woo hooo, time to sell and don't crunch actual numbers (selling costs, stamp duty, bank costs etc).
I won't be ever selling this place, I'll use it in a different way, but still make money.
Bath had a different plan etc etc. You gotta have a plan.