I can't find the original post, but low value definitive UK stamps i.e. 1p. 2p. 5p & 10p - are NOT being phased out according to Jane down at my local Crown PO. As she said, they are very useful to add to underpaid postage items presented at the counter for weighing and checking.
The 3p. 4p. 5p, 7p, 8p, 9p, etc went a few years ago.