I don't actually think there's as many left as some are indicating. There are only 3 blocks available to choose from in the lower tier now, and while there are seats available in loads of blocks in the upper tier, it seems to be just the back few rows in most of those blocks or the back few rows of each pricing band in those blocks with 2 different price bands. For example, block 551 has 2 price bands - 2 and 3 - and 39 rows. For price band 2 (the £50 tickets), it's offering a seat on row 23 which must be close to being the back row of that price band in that block, and for price band 3 (the £40 tickets), it's offering a seat on row 37.
I reckon there's probably only 3000-4000 tickets left