I've never been a size 12 in my life (OK, perhaps when I was 12, lol) so being that size just seems like Cloud Cuckoo Land to me! But you know, reading these success stories - I might even get there too!!...
I have also found tesco's to be a bit more 'roomy' I have a pair of 18's that are fully falling off me now that i've lost weight.. and massive on the leg, but then a pair of slimmer 18's from new look that i've only just managed to get into.