Hi verney - Every year about May Ilford announces their ultra large format film special. You should see the announcement here on APUG. You can order as many boxes as you would like, there is no longer a minimum order during the special order period. So if you were the only one ordering 2 boxes of FP4+ half plate film that would be fine. Ilford has been very accommodating to ULFF photographers. You just have to remember to look for the announcements in the spring. My advice is to order enough film for at least 1 to 1 1/2 years worth of photographing, since the special order is once a year.
Fred Newman