Dress for black tie event

[Workisntworking]

I am attending a black tie event in a few weeks.
Its been a while since I attended such an event and since then I've grown and fashions have changed.

Ive been looking online but just dont know what to buy.
I'm a size 16, 5'7", flabby tum.
Id rather cover my untoned arms and prefer a v-neck to avoid a matron bosom.

Does anyone have any pointers?

Budget wise, Id rather not spend more than £150 as cash flow tight this month.

I used Girl in Mind last year for a dress for a wedding. They have many many styles suitable for lots of occasions. Prices range from £45 - £80. They go up to size 18 and i found them true to size. I ended up buying 2. Did returns too. No issues