If there are new houses still for sale in the development then you do realise you'll be selling a property which, more than likely, will need stamp duty paid on top of the asking price. The top price you're likely to receive is then (latest developer price - stamp duty liable).
Also you'll now have to pay Stamp on your next property AND there's less mortgage interest relief as a 2nd time buyer. So you may want to slap some of the profit in the bank. FTB status is generally worth about E13K. Just don't don't go mad on the oul Ferraris just yet is all I'm saying.