Hi all,
Not been on this forum for a while but I thought I'd pop by as I was out shopping and couldn't believe that I'd found such value tops. When I was looking 2 years ago I ended up at mothercare and paid a good £20 per top.
So, If you're currently looking for some nice lightweight (and very simple) t-shirts for BF, then if you're passing Peacocks, pop in. I can't find them online but they were £6 each and was a simple t-shirt with a white layered effect under but the white bit only goes to just below the bra line, so not as much to lift up (while you pull the other down) and you don't get as warm - much better than my old mothercare ones...
I hope this is useful to someone... I'm ttc atm and have bought 3 
Power of positive thinking!