As is mentioned by the PHP UK Conference organizers, this year's even is almost sold out, so you should get your tickets while you still can!

PHP UK Conference 2011 is PHP London's sixth annual conference. [...] The PHP UK Conference 2011 is powered by PHP London, a limited company of the UK. The conference planning committee is made of up the PHP London executive committee and additional volunteer members.

The ticket price for this single-day conference (with a full day packed with sessions on topics like advanced OOP, agility in software development and mobile PHP applications) is only £130 VAT and can be purchased directly from their site.