Based on some previous threads here.. if you have to pay in full before ordering I would be very wary.. Homebase and B&Q aren't dedicated kitchen providers and so have some problems.. Noyeks would do better I'd imagine.
Yeah,, so if paying up front in full I would pay by credit card if at all possible.. even if this means paying some money, clearing the bill, waiting a few days for the money to clear, then paying another installment etc etc.
Make sure you get in writing what you're due and don't sign for deliveries unless you have checked the goods or else written 'unchecked' in the docket beside your signature.. writing unchecked is more common as delivery guys often aren't prepared to wait.
You could consider asking for an extension of the sale until Friday for example.. if you want to check out more options.
A half price offer does sound good.. but they may be more expensive to start with.. and many places are having sales at the moment.