WCollins has it about right. I've written quite a few for 'Pilot' (and my last cheque was a bit more than WC's £600 ;~).
I haven't submitted anything under 'Pilot's' new regime (or anywhere else for a while for that matter), but when James Gilbert was in charge, he paid on acceptance for articles, on publication for pictures (becuase untill they lay out the pages, they don't know which pics will be used). Flyer had a reputation for paying less, paying late, and sometimes needing some propmting to pay at all.
Good quality pictures are important. If you can write, you will suffer little interferance from the editorial red pen - at least that's my experience. Except my last article, where they publishsed the second paragraph first, and the first one third (IIRC). It still made sense, but I thought it detracted from the 'flow' of the piece.
I think James was quite generous compared to others re fees (but had high standards and 'knew what he wanted'), but I don't know if that still applies at 'Pilot'.
SSD