I would not buy nursing bras at this stage, it's likely they won't fit when your milk comes in (I went down a couple of back sizes and up a few cups, for example). You can wear normal bras, just get one in your current size.
I bought a lovely Freya Dotty from eBay in a 34H. Bravissimo do nice Freya ones, and John Lewis own brand are quite good too - they do packs of two that are quite pretty and reasonably priced, in large cup sizes.
I am wearing Triumph Doreen bras at the moment. They're not specifically maternity but non-underwired. I'd be lying if I said they were things of beauty and they do have an air of the older lady about them but they are lacy, comfortable and supportive and the shape under clothes is ok. Three hooks at back and thick straps but I don't see how you could avoid that with large sizes and no wires. The support has to come from somewhere.
Yes definitely go to bravissimo if you can. They will fit you properly for a start, as most women wear a bra that has a back size that is far too large plus you need some give in a nursing bra as your boobs grow and shrink depending on the feeding cycle. And they have some really pretty softcup bras.