Sorry I haven't read all the replies so sorry if I'm repeating but here are my opinions, for what they are worth!
Under bump is great at the start but there comes a point where only over the bump (with stretchy but supportive panels) trousers/skirts are comfortable. On the bump, imho, never works - they just fall down.
Bump bands are great - aside from their avowed purpose, can also provide a bit of extra support on those achey bump days.
Moda from Mothercare despite all my snobbish prejudices is actually a very good range - they cut tops long enough unlike many ranges. Long is vital in mat wear. I actually have loads of stuff from Mothercare & it's some of my most worn stuff.
I personally find Mamas & Papas overpriced & am not sure they are good enough to be worth paying the extra for. (And again I start grumbling to myself about the M & P on the bump linen trousers that I should have known better than to buy ...)
Isabella Oliver, on the other hand, is worth spending money on, if you feel the need to invest in one special item, for example. The long, jersey, black skirt with the over the bump panel which is usually in their range is without a doubt my most comfortable/worn item.
M & S normal clothes I find cut quite generously around the waistline - I think their target customer is a post partum mum!) - both times I have found one of my most comfortable/respectable items once I get to about 7 months, is a pair of their normal, non maternity, smartish jersey wide legged trousers. The waistline is cut generously & stretchy enough to come up all the way over my bump - I didn't even need an enormous size. I got this pair last pregnancy (2 years ago) and wore them loads in the last 3 months, but they still look smart enough to be my stalwarts for the last 3 months this time too. Obviously you need bum covering tops to wear with jersey trousers, but if you bear in mind my previous point about long tops you'll be OK!