Wiggle are currently selling the 2XU ladies compression sock at half price. I have used their calf guards, and got on well with them. I think Karrimor do a compression sock, if you want a really cheap one to test the principle.
Presumable this race is the Stour Valley Path 100k. If so then it is a pretty runnable, course, though the local farmers occasionally plough over the footpath in places. I ran it in Salamons, though I don't think there would have been a problem with road shoes.
Polls are an advantage on some types of terrain, and a hindrance on other types. The folding ones are much easier to stow away when you don’t want them. Naturally then cannot be made as strong as the telescoping type.
The two models that you have mentioned seem to be the most popular among ultra runners. If you are going to go down the route of poles, you want to get some practice using them on training runs, to develop superior technique. If you have a friend who owns a pair, then borrow them for the day, to get an idea what they are about.