Many of the European tickets go on sale today at 9 and 10AM GMT.

TicketMaster UK has the following tickets listed (as of this posting) available for sale today:
Sheffield, Manchester, Glasgow, Belfast, London, Birmingham, Madrid, and Barcelona. Other shows going on sale today can be found on the tour page.

[+] Update 4am EST (9am GMT): Tickets for Barcelona, Madrid and Belfast are up and available for purchase. Folks attending UK shows can pickup pre-sales at IdiotClub.com.

[+] Update 5:20am EST (10am GMT): Tickets for all UK shows are now available.

[+] Update 6am EST (11am GMT): While many tickets are selling out fast, you can still find some seat tickets at gigsandtours.com. Looks like most standing tickets are already sold out.

[+] Update 9:15am (14:15pm GMT): Green Day added Wembely Arena to the tour. TicketMaster still has tickets.

Prices are around £35. Some shows have a two ticket limit per credit card/per person. If you need more than 2, ask a friend/spouse to help you out. Keep an eye on the TicketMaster UK site for all the available shows.

More tickets coming up tomorrow. Ticket links and more dates can be found on the tour page.