It'll be an official Asian version but there'll be a customs charge to pay, probably VAT + a fee.
I've been doing the maths for the likes of pricejapan and other Japanese middlemen and a Japanese version will still come in at around £520 all in so for once the UK price of £549 isn't a huge rip off. I can't for the life of me pre-order from Sony though. What a truly useless website.
the actual cost from Price Japan worked out at £480 delivered to UK (FedEx)..
Accessory-Jack will do you a deal on Customs but you will have to ask before you purchase, the actual price incl shipping is £455 not sure about tracking but will probably be EMS.