ooo oooh....almost forgot one!
Simply Yours - the finest range of underwear, lingerie, corsets, basques, shapewear and hosiery - Simply Yours - Simply Yours
Also try their sister website Simply Be - a fashion catalogue that offers a wide range of fashion for all occasions in sizes 14 - 32 - Simply Be
Got a simple corset from them in their sale for under £20.

I suggest browsing both coz sometimes one of them has the item you like on sale.

kisses x