I thought I'd update this thread to say all went well, very hard work especially getting down to the foundation, but the steels are all in and the BCO is happy with it. Took a total of 7 days (a 4 day weekend and a 3 day weekend) from installing the acrows (I put needles through the weekend before this), just myself and about 25 hours of assistance from my brother. PS The OSB wooden construction is temporary for security and protection from the weather, most of the timber frame will be re-used for the decking base.