Thanks everyone- it’s my husband’s friend so didn’t want to take any chances but it looks like the consensus is that it’s not too white.
The wedding is a church then a converted barn so I don’t think it’s super formal (Although I hadn’t even considered if I need a fascinator/hat? I don’t think many people have worn them at other weddings I’ve been to, but I wasn’t paying much attention).
I could do a relaxed blazer/jacket instead of the cardigan if I needed to, I was just hoping to get away with not buying one (I can’t imagine that I’ll wear it much).
I did consider buying the second dress too just for holidays and evenings out, but I’m definitely not super tall and slim so sadly I think some of the comments about it looking frumpy might be fair.
I might buy the dress and try it all on together. I have some lighter coloured and some metallic shoes and also some slightly more formal ones so I might see what looks best.