Sarah and Elijahfan: have either of you ever tried a large bookstore like Barnes & Noble? I know the B&N's here, in the States, offer a wide array of magazines, including UK imports like Vogue, Tatler, Hello!, Harpers & Queen, and even teen Brit magazines (which often feature Keira) like Sugar (how else do you think I stay on top of collecting all my Keira magzines?

) I would think the same would go for the US magazines and their availability in the UK. I could be very wrong, though, as I've never been there.
And if all else fails, there is always Ebay! I have purchased many-a-Natalie Portman magazine on there in the past (all the way from Italy, Japan, and the like) and it's all relatively inexpensive, depending on what kind of mag you're purchasing. I know for a fact the Interview mag is for sale on Ebay right now (from at least two different people).
I'd love to help you out personally, Sarah, but I don't think I'll be buying that Interview magazine and I already own a copy of Vogue UK. But, I'll do the next best thing and post the first scans available on the Net of the lovely photos (I'll post scans of the article, too, once they show up).
They're rather large scans, so I'll just link to them:
EDIT: It seems they don't allow linking, so, just make your way over to
NataliePortman.de. They're the first things you'll see on the main page.
Enjoy (and let's hope I don't get repremanded for posting Natalie Portman pictures in a Keira Knightley picture thread!

)