It is certainly worth checking your local PC World stores. I placed an order on the Apple website for the 64Gb 3G model. I got an estimated dispatch date two weeks hence. Not too bad, but I checked on the PC World website, and was able to reserve and collect one later the same day from their out-of-town store near Southampton. I know there have been some complaints about service at PC World, but my experience was absolutely fine.
My impression, from several sources, is that the 32Gb models are in very short supply, but that 64Gb (and, to some extent, 16Gb) is easier to come by. PC World seemed to have 20+ of both 64Gb models in stock at that one store, a smaller number of 16Gbs and no 32Gbs at all.
