Initial stock has sold out, so if you order you'll have no chance for a console on release day. Amazon has stuck up a notice on its listing for the Xbox One that if you ordered after November 14, you probably won't receive you shiny, hulking Xbox One before Xmas.
On the PS4 side of things, it seems to be a similar story. If you ordered before August 6 you'll be unpacking on release. August 7 to November 13 and you will receive it before Santa arrives, after that though Amazon just states that you won't receive it before Christmas.
The grocery giant will, of course be selling both consoles. If you're looking online, then you're out of luck as both are sold out. See, it pays to pre-order. Not all is lost though, Tesco has announced that it will be opening some of its Extra branded stores at midnight and it will have stock of the Xbox One, though we doubt very much. Finally, some Tesco Extra stores will even pimping up their exterior signage for the big occasion.
We'll have to wait and see what happens with the PS4, though if they do it with the Xbox One; we'd hope it will be the same come the 29th.
The once high-street chain turned online only business seems to be mostly sold out of PS4 consoles, though after a bit of digging it appears they have one bundle which still has limited day one availability. However, it's a monster bundle. Costing £629 (nearly £300 more than the console) you'll bag the PS4 itself, an extra controller and six games, including Fifa 14, Knack and Killzone. Is your wallet wide enough?
Things are little bleaker on the Xbox One side of things, with no stock expected until December.
Online first, Asda are still taking pre-orders for the Xbox One and at the time of writing, they seem to be available for delivery before Christmas. Playstation wise, they are advertising day one stock, though only in very small numbers, so it's best to be quick.
Asda is also offering another sweetener for PS4 buyers, letting you save £5 on a selected game when you purchase it with the console.
In-store seems to be dependant on the size of store as to whether they will have free stock going, so its best to check directly with your local branch.
As you'd expect, Game have a whole load of bundles and options available to you if you're looking at getting on some next-gen gaming hype. In-store, midnight openings will be taking place across the country, though it seems that this is just for people who have pre-ordered, not for walk-ins. Again, best to check with your local branch directly to see if they will have free stock, though don't get your hopes up.
Gamespot is still offering the console duo for purchase online, though it isn't giving exact shipping dates apart from the warning that if you ordered after September 5 (Xbox One) and September 1 (PS4) you won't receive the console on release day. Gamestop is competitively pricing the Ps4 as well, with it available at £329 – a nice £20 reduction.
Another online retailer, another vague idea of shipping dates, though Shopto does say that if you place a pre-order now, you will receive your console of choice before Christmas.