Smart summer trousers - tall with a tummy - do they exist?

[OvertiredandConfused]

Casual trousers (skinny jeans, chinos, linen crops etc) I can find okay but I really need a pair of smart trousers, ideally in grey, that I can wear for work over the summer in an office with a smart dress code but no air conditioning!

I'm 5'10 and, in trousers, a size 14 long (inside leg about 33"). Dresses and skirts I'm a 12 but I have to be careful what I wear as most of my 10lbs excess weight is on my tummy. Means I really need trousers to at least sit on my waist. Ideally slim leg as I want to be able to wear looser tops and pumps as well as heels.

I'm 45, fairly classic style. Hate feeling middle aged and invisible but work dress code means I have to be sensible. Don't want to spend a fortune but willing to go to about £60 for a decent look and fit.

Is it impossible?

I have these ones

I like those KiaOra. But they're sold out in a 14. What's the length like?

How about Oasis? I got a pair of black (so obv not grey!) smart trousers from there the other day. I only have a 30.5" leg but I have had to turn up the hem so they have a cuff at the bottom when they are supposed to be worn straight and they still aren't that much above my ankle.