I wear a thin stretchy strapped vest top underneath whatever top I want to wear that day. You just unclip your bra and then reach up under your top to pull down the cup and the vest so it is under your breast. You then lift up your top and latch baby on, top falls back down to cover breast and the vest covers all your back and (in my case squidgy) tummy that way you don't need to worry about how floaty the top is as you are already covered.
I have loads in co-ordinating colours to match my tops. I get mine from Primark they about £1.50 each so you can get lots and they won't break they bank.
I also have two 'proper' nursing tops one from H&M which I dislike as it makes me feel exposed (there are 2 panels which you part to reveal your nipple so you are relying on baby co-operating and not popping off).
I also have a Blooming Marvellous one which works a bit like my vest/top combos in the sense it has a panel you lift up to nurse but the panel then covers baby's face.
I have a nursing dress from JoJo Maman Bebe which is really pretty and my mother in law used as a template to adapt some dress patterns to make me two more nursing dresses for three weddings I went to last year. They were all in the same group of friends so I couldn't recycle the same dress over and over.
I really like the one that is in the current catalogue it's really pretty.
I would caution you to stay away from the mothercare nursing tops as unless your breasts grow either side of your waist you won't find them very discrete! I bought one and took it straight back as you could see my back, tummy, sides and my breasts! Not what I want other people to see.
Just to note I don't have any problems with people nursing however/where ever they like and however much skin they show but for me I am body concious and have issues with MY fat being out there for people to see. I could give a rats about other people's fat!
Good luck and don't forget you will lose lots of baby weight in the first few months so don't go crazy buying lots to fit your 'new' shape as it will probably be changing soon!