Nike seem to size their spikes about 1.5 sizes larger than normal foot size. e.g I 'm 7.5 and take 9 in Zoom waffle spike XC xpike things..., 8.5 in some nike and 8 in others. 8 in Mizuno, 8.5 in adidas... etc.
UNless you know your size , the 40 mile round trip is well worth it! (about £5 in petrol???)