Hello moggyjim.
Even though the VHGMC have a marquee and presence at the GDSF you have to book a machine in via the GDSF section leader or through Show office, details are on their website.
The section leader for the Horticultural section is Mrs Christine Ricketts 01258 452984. if you phone her she will probably be able to put you on her list. You will probably still have to get an entry form from show office and submit a photo of the exhibit for their approval.
Good luck.
Chris