I'm 30 weeks and started wearing maternity stuff at 16 weeks.
Mostly bottoms, I prefer stretchy tops and have just bought my normal Primark/Gap t shirts in a bigger size and am still wearing my old cardies, jumpers etc over the top.
Things I love and am wearing lots -
Seraphine cords - makes a change from jeans, bit smarter and warm in this ongoing winter we seem to be having. Seraphine sale. Something to think about if you are goimg to be pg in the winter.
Blooming Marvellous mock wrap dress - black (of course) - very comfy, smart for work, great for when I get fed up of baring my tummy to all and sundry! fiver on Ebay.
Gap maternity chinos - fab. In fact all Gap maternity stuff = fab, if you can fidn it. And they alwasy have a sale rail.
Flat Mary Janes with velcro stap - I have had these for years and am wearing them all the time now. The strap give my big wide feet and expanding tum a lot of support. The kind of thing Clarlks might sell as school shoes.
Lace up shoes- At about 6 months I found that lace ups gave me much better support than slip ons/flip flop/ballet shoe style. Shoe of choice is Converse trainers, am collecting colours to break up all the beige and black that mat clothes seem to come in.
Grey work trousers . JojoMamamne - Boring but comfy if you need work trousers.
White blouse - Scarily large white blouse which cinches in at the back and actually looks quite smart. Mothercare. Again, if this is the kind of thing you need for work.
Roll top trousers - Peacocks cutrrently have black or grey roll top yoga pants in their maternity nightwear range. Look OK and at only a fiver, not bad if they only last a few weeks (in quality or size!)
I got a lot of stuff from friends and Ebay which was handy.