In regards to underwear, buy a whole bunch of men's underpants! They are the best, they are so comfy and durable, they have thicker material at the front so less chance to leak and they are nice and big and supportive. I've been wearing my OH's undies a lot lately and they feel fantastic, I'm going to go and buy a whole bunch for after my birth to wear around.
Re bras Asda are doing 2 sports bras for £6 or £4 each and i'm finding them really comfy and you dont have to worry about the cup size as they are stretchy.
And my hubby has been telliing me for ages to wear his knicks but I think it is just a ruse so I will let him wear mine, I am not falling for that