KickassTorrents, H33T and Fenopy are now all blocked in the UK. The Pirate Bay saw a similar fate last year. As with The Pirate Bay, web proxies for all of the sites are bound to pop up.Even now, there are plenty of options for fans of the sites affected by the censorship. Probably the best option is a good quality VPN, this gets around the block and adds a bit of anonymity to sharing files via BitTorrent. There are plenty to choose from.
If you can't afford a VPN or don't want to use one, there are a few tricks you can use, a simple one is enabling Turbo mode in Opera. In essence, this works just like a VPN would, traffic is directed through Opera servers, bypassing the British block.
Even easier than that, you can use Come.in, a site created by TorrentReactor, which acts as a simple reverse proxy.
It works for TorrentReactor, KickassTorrents (Kat.ph), The Pirate Bay and Torrents.net for now. Because ISPs block the IPs and domain names to block sites and because a reverse proxy doesn't use either, you can freely access all of the sites listed.
UPDATE: There are obviously many other reverse proxies out there. Come.in seems to be working OK, but if you can't get it to work, you can try some of the ones listed in the comments.
Note though that logging in won't work on most, probably any of them, so you won't be able to use your account. Everything else should work properly.
If Come.in is having problems, Katproxy.com also works and seems to be popular. It may even let you log into your KickassTorrents account.
UPDATE June 10: Most British ISPs now block a long list of proxy sites, including Katproxy.com. While some proxies still work and their owners are looking at ways of bypassing the block, it will be a bit harder for UK pirates to get to the sites they need.
UPDATE June 13: Kat.ph is dead, it looks like KickassTorrents lost the domain, but luckily it found a new home. You can find out more here.
Update August, 2013: There's now a very simple way of accessing any of the blocked pirates sites not only in the UK, but pretty much everywhere around the world, the PirateBrowser, a custom version of Firefox designed to bypass censorship. You can find out more about it here.
PirateBrowser is available for download here on Softpedia.