I might be purchasing one of these ready for my region digital switchover on June 13th so I've made a few enquiries.
Panasonic Lakeland store are expecting their first delivery at the end of May @ £499. They claim that there have been no supplies of this model in Europe yet.
John Lewis Bluewater quote an "after May 14th" date for delivery but, to save time for anyone enquiring later, their stock number is 85871109. Price £499
The cheapest pre-order price that I've found is at Forum hifi, Nottingham @ £470 inc VAT, delivery and 1 year warranty
www.forumhifivisual.co.uk
They don't expect much stock on the first delivery but have a "waiting list" that you can join.