Not to put you off, Fran, but I think it's not quite so cost effective with MCalls and Buttericks. In one of their sales McCalls are $3.99 which would be $3.20 for BMV members. So if you buy 3 and pay $15 for postage that makes it about £19 for 3 patterns in total if I have done my sums correctly (not factoring in the BMV member cost but that soon pays for itself over a year if you are buying regularly). Hmm it is still a fair bit cheaper than full price UK though. Definitely worth thinking about if you buy patterns regularly.
Apart from a hiccup last autumn when they changed systems and were a little bit slower I've always found them to arrive reliably in 10 days. In fact I can see a little parcel waiting to leave Chicago for me now!
The one thing to be aware of is customs charges. Keep your patterns cost below £15 and you should not be charged tax. The only time I've ever paid tax was the first time I cheerfully loaded up my shopping basket with well over £15 worth before I understood the system. After that I stuck to the limit and it was fine.