Wedding guest dress advice!

Hi everyone in our little corner of the internet. I am ferociously googling wedding guest dresses and the moment and I had joined this community and thought why not ask here! Does anyone have any advice on where to buy a good wedding guest dresses - preferably online. I’m based in the West Midlands though for shop recommendations.

I’m a size 16 hold most weight on my lower stomach and prefer to wear sleeves. If anyone feels they may be of any benefit or know what suits that still body PLEASE HELP!