Taking Shape is a good alternative. It does have its fair share of yawnsome tunic tees and waterfall cardigans, but what plus size retailer doesn't? If you can see past the 'classics', there are also printed sundresses, floral day dresses, flippy '40s style skirts and summer maxis. Prices mostly come in at under £80 and they stock up to a 26.
the polka dot skirted swimsuit. Because it'd be rude not to.
Anthropologie and wished they came in bigger sizes, Ruche is your transatlantic saviour. Their 'Curvy Plus' range may be small, but it contains some real gems, particularly in the retro party dress department! The sizing can be a little limited and stock seems to sell out before you can say "I'll have the black stripy one please" but it's definitely worth a look for special occasions. International shipping is based on weight (so bear this in mind when choosing fabrics - jersey maxis will be pricey).
Elvi does a good line in tailored dresses, the occasional killer party frock (see the red floral dress above - I'm a sucker for jacquard as it sits so well without creasing) and pretty blouses. Of all the retailers on this list, it skews the oldest, so if you're looking for slightly longer hemlines and less trend-driven fashion that'll stand the test of time, this is the one for you!
MYNT1972 are your saviours!