Price is likely to be ~£999-1029 as the £:$ has risen but AMD will want to try and keep the card targeted at below the psychological below £1k barrier, so may well support the price even if it drops back a bit in the next few weeks.
As for buying a card on release, if you aren't willing/able to sit in front of a device and spam refresh for 10 minutes, then you probably won't get one until the new year in terms of just loading a website and hitting add to basket, and if you want an MBA card it depends how long they offer them for, they may start offering them long term via a UK outlet like Nvidia does with the FE.