>>> anyone done a supermarket dash literally in the final hours of >>> Xmas eve?
>>> Are the shelves all nearly empty?
>>> Have a got a (fairish) chance of finding enough things reduced >>> to knock up seafood platter?
>>> Are the supermarkets really empty so late on a xmas eve or still >>>> packed with folk?
I usually go shopping just an hour or two before the shops close on Christmas Eve. (Don't forget that they often close quite early!). I do so not because I've left everything until the last minute but because I like the atmosphere and it's a good time for a bit of people watching too ;-)
I find that the stores are generally still quite busy but probably rather less crowded than they were a few hours before. It can be a bit hit and miss if you're looking for particular items though. For example, one year I couldn't find any type of cream (single, double, whipped, clotted, brandy or anything else) at all to go with my Christmas pudding in three different supermarkets. The following year, at the same time, I could have started my own dairy business with all the cream that was on the shelves at the same time of day.
Finding short-dated bargains can be a bit trickier than you might think though. I've often checked what I call the "cheapo chuck-out shelves" in the hope of finding heavily discounted stuff but I've generally either found those shelves all but empty or with hardly anything knocked off the prices of the items on display. Again though, it can vary greatly from year to year. In some years, for example, every store seems to have loads of Christmas cheese (Stilton, etc) on offer at perhaps only 10% of the original price, whereas in other years there's not a single piece of cheese on offer at all.
Things might be a bit different this year as, for example, Sainsbury's are running a big radio advertising campaign, encouraging (nay, imploring) customers to do their 'last minute' Christmas shopping on 21st and 22nd December, rather than on the 23rd and 24th.
Further, in previous years all the major supermarkets (except Waitrose) have only closed on Christmas day, with trading resuming on Boxing Day. (So there weren't that many products which would reach their sell-by dates when the stores were closed). This year Asda has bowed to union pressure and agreed to keep its doors closed on Boxing Day as well (so there might be more short-dated bargain in Asda and Waitrose than in other supermarkets).
With regard to your hopes of finding stuff for a seafood platter, don't forget that most of the major supermarkets have now closed their fresh fish counters. Only Morrison's are retaining their specialist fishmongers.