Where can I buy GOOD cotton?

[PoppyAmex]

Sorry, it's probably a stupid question but I'm a newbie.

I want to make cot sheets/pillowcase and am looking for nice high thread count cotton (or flannelette if this isn't possible) - does anyone know where I can get it online?

[ChocolateCremeEggBag]

I made DS's cot sheets from a large (old) bed sheet - I would therefore try tk maxx for high thread count flat sheets and cut it into 4 and hem.
I think this might be your cheapest option and you'll be able to feel the cotton too

I have looked for flannelette and best colours I can find are on the quilting sites but will be upwards of £10 per metre and ,at not be 100% cotton.