If you reserved in August 2016 and Barratt have only just finished the foundations, you have to ask why it has been left so late to start a clearly known sold house when they want it for their year-end figures.
Read this article which shows the lengths builders to go to force buyers into legally completing even on unfinished homes, just to get their figures!
Unless you bought on an "early bird" and were told at the outset, that the home would not be started for a few months, this needs looking at. In addition, most housebuilders require you to exchange contracts within 28 days. Quite why six months later you haven't done so is another mystery.
For a comfortable construction period that allows for intangibles such as the weather, holidays, material shortages and late deliveries, a normal two-storey new house should take between 18 and 22 weeks to build. It can be done quicker as a one-off provided no other houses are also being rushed (not the case at builder year-ends)
Provided you haven't used Barratt's recommended suggested solicitor, I would advise that you inform Barratt that you cannot legally complete until August 2017.
However, if you do this, at this stage work to your house could be stopped to prioritised those for year-end.
In any circumstances, do not legally complete until your snagging inspector has checked the house and all items in his report have been attended to.
If Barratt cant or wont agree to this walk away. After all this time you can get most of your Reservation Fee refunded as well as any related expenditure such as legal fees Using the
Consumer Code for Home Builders