Make your own, it's much cheaper and just as good. I bought an 8m x 4.5m (if I remember correctly blue tarp from B&Q for about £15, then laid it out in the garden, pitched the tent on it and used a marker pen to mark out the size of the tent. After I packed up the tent I just cut the tarp to size ensuring that I cut 15cm ish smaller than the marked size to make sure the 'footprint' didn't protrude out from under the flysheet and collect any water between the SIG and the footprint.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.