One thing i have learned is that people always drop out!
so don't worry, even if you haven't got one now nearer the race people will suddenly find ways to cancel on their mates that bought the tickets

last year at the practice a late addition to our group got a Dunlop grandstand seat and general admission no probs. I will agree that camping esp MB will be trickier (gold dust?) this year but several companies will have at least the odd ticket if your not looking to group book.
Theres always the other site that were not supposed to mention with a camping area in bsj.
I have every confidence you will be able to arrange something. I may even be putting up an add in May.
Baron Blanc