Belated thanks to everyone, and to Scotmum for the tip about 30% off at Gap that day. Some of the Gap maternity ones are fab - their modern boatnecks are really good quality, warm, and ridiculously long in the body to stretch over my expanding bump. Some of the other Gap ones are ok but a bit thin. Nice long arms and body though.
Jojo Maman also had some decent ones in the sale though they have weirdly baggy arms. I'll try some of your other recommendations too.