It's a nightmare.
The only shop that sells near me ( and I live in a destination shopping town) is JoJo. They don't even sell normal vest tops - the only ones they sell have an incorporated bra for when you want to not wear one (as if with my norks!). Their leggings are all made for people over 5ft 6 - they would cover my feet and it's just all a bit too mumsy, although the quality is good.
I bought vest tops from New Look online. Dreadful. They had no spring to them whatsoever, large, shapeless and the white was see-through. They went straight back and because returns are not free, the 'trying on' experience cost me £5 :(
I wanted to order from Gap, which is now only available online. I threw my toys out of the pram at this point, as I had a £70 credit voucher with Gap, but they would not let me use it online, or send to a store and pay then, so I told them to stuff their maternity wear.
I bought a dress from Asos, which was horrid. Nasty, cheap material and a neckline so high that I looked like I was smuggling balloons. It went straight back, luckily free returns with them.
I eventually ordered 3 maternity vests from Next. They were not bad, but looked nothing like the website. They were ribbed cotton and not smooth. But heck, by this point I was getting desperate so I kept them.
I'm 6 months and that is all I have bought.
By some miracle, my normal jeans are still fitting under my bump and I may just buy those extender things to make them bigger if I need to. I have extender clips for bras left over from last pregnancy.
I have a few regular tops which are longer than normal which are working out ok. Plus a few dresses that are just bulging with the fabric to fit the bump (I am aware I am probably ruining them...). I have found shirt dresses work well and tunic style dresses as long as they are cotton / a bit stretchy. Cardigans are fine as long as you don't desire to button them all the way down.
But overall, yes, a flipping disaster. I can't wait until I can shop like a normal human again...