I might add that last year, Comet in the Forbury put one aside for me when I walked in in the morning and asked nicely.
Also, John Lewis gave out numbers before the launch, although I doubt they do it this time due to it being early.
And last but not least, PC World in the Oracle had a surprising amount of iPads and quite a short and well-managed queue. They closed shop and then reopened just for the launch and let people in one by one.
All in all, my launch experience in Reading, sans Apple store, was much better than at most of the Apple Stores around the country (I only queued for 30 mins to get exactly the one I wanted from PC World), so my inclination would actually be to go somewhere OTHER than an Apple Store...