I think I might know the ones you mean JacqB, i was looking at those too, soft cotton quite wide straps.
I got my front fastening soft bras from M&S, a bit pricey at £20 but very comfortable - I'm still wearing them 11 weeks post op.
The ones I used immediately after my mastectomy were from Anita, sports bras with hooks/eyes. My hospital recommended them. They don't however have pockets to put a prosthesis etc into.
Any recommendations of where to buy nice soft front opening bras? All I can find is zip ones but I am presuming I need ones with poppers/fasteners?