hi sueellen,
i designed my own unit from a basic square. have 3 rooms. insulated roof and floor. 2 sngle, 1 dble, window and a french door. all dble glazed and tilt and turn. erected in 2 days. have to do all of the treatment and varnish etc yourself, and also have to have your own level base although the company can do this if you want. you also put in all your own services like water and esb, but these are accomodated if ready when the unit is being erected.
i don't want to name or give a firm recommendation or otherwise yet until i get to the bottom of the water problem.
if you want any more details feel free to email or pm.