Managed to get one from Jessops - ordered it when I bought the 5D3 about 2 weeks ago, and it was in the shop within 4 days. They also had some to order on their website last week, but think it is back to pre-order now.
P.s. The BG-E11 is VERY nice - much more sculpted than that on the 7D and other EOS' I've had in the past, so feels much nicer to hold, in portrait position especially