Yeah, the ones Ike mentioned. Personally, I’ve bought most of my figures from [HLJ], and never had any problems with orders, except for one which they cancelled on their end because of high demand. [HobbySearch] also seems to be good, but I have only one experience with them (but everything arrived fine). [CDJapan] is another, they are very reputable, but I haven’t ordered any figures from them (yet), they’re slightly more expensive, but they seem to take great care of packaging orders. I did order some Headphones from them, and again, they arrived fine. Also, I assume you’re aware, but in case you don’t: you’ll need a credit card. I don’t know which shops accept paypal or other methods.
About custom charges: as these are big, legitimate business, they do things officially, which is to specify what’s in the package and what its value is. Which means you’ll always get hit with custom charges. At least I do, here in The Netherlands. I’ve learned to live with it. The thing is, even with the customs charges, you’re cheaper off. Just take it into account. Just compare £ 50,- plus shipping to € 26,- with shipping and some customs charges. Furthermore, at least in The Netherlands I can order something with a value of up to € 50,- or something wihout needing to pay customs charges. I imagine you’ll have something similar in the UK.
Lastly, 2 additional shops:
In the past, I’ve ordered games / consoles, and DVD’s from [Yesasia]. They’re also good, but very expensive. However, they seem to have some weird business construction where they ship orders through Germany. I never had to pay any customs charges with my orders from them. I don’t know if that’s still the situation, and if that also applies to the UK. Another advantage they have, is that they’re not a popular choice for figures. If something’s sold out everywhere else, you have a chance they may still have it. Finally, there’s an European shop, [Archonia]. They’re generally more expensive, sometimes not, sometimes to a ridiculous degree, but since they’re European (Belgium), you’re guaranteed to not having to pay customs charges.
For your convenience, I’ve listed the productpages of Figma Link for each site I mentioned.
http://www.hlj.com/product/MAX06243/Act
http://www.1999.co.jp/eng/10189772 (but I see they’re not accepting any more pre-orders)
http://www.cdjapan.co.jp/goods/goods_detail.html?KEY=NEOGDS-88223
http://www.yesasia.com/global/figma-the-legend-of-zelda-skyward-sword-link/1031027138-0-0-0-en/info.html
http://www.archonia.com/mangashop/en/article/160294/the+legend+of+zelda+skyward+sword+action+figure+-+figma+link+re-issue+wave+02/