Gosh, it would be so much easier if OPs put all the relevant info in the first post, rather than having to have it dragged out of them! 😂
Evening wedding in a barn. Size 14, no black, prefer trousers. I have no idea what your perception of a small budget might be. (A specific figure would help!) As you haven’t mentioned your height I guess we can assume ‘average’ and not restricted in what you can buy?
I’d suggest a cord or velvet trouser suit in a seasonal colour. You can get them at any price - last year there was much S&B excitement over something lovely from one of the supermarkets (maybe Sainsbury’s?).
You may have to wait a week or two for the full autumn stock to appear in shops.