Just back from dragging DS round Bluewater (shopping centre) without a pram.
I ended up piggybacking him as it was the least heavy option when he was moaning that he was tired.
However, I can report:
Gap's maternity things are okay, but you have to keep in mind that the sizing is odd (half American, half UK), and not panic that they don't have anything in your size.
John Lewis seems to only do its maternity stuff online, which is not terribly helpful as far as I'm concerned.
Next things were pretty hideous, all floppy and did not suit my figure (tall, curvy) at all.
Dorothy Perkins was a surprise hit - much more classic designs, and I got a nice normal pair of flared jeans there (the flare distracting from the swelling bump further up the leg). There were some pretty and classic dresses, but - alas! - they required a smaller bust!