Smart casual help

[LlamaBananas]

Have just got a new job which is very very image concious with vvv strict uniform and grooming code.
Im doing a weeks training before i start and get issued my uniform. I had assumed it would be smart clothes which i have a couple of options on (my interview suit and blouses) but the info pack arrived yesterday stating to wear smart casual. No jeans. No trainers or similar.
Im early 40s. Mum and ft student up until now. My wardrobe is jeans and more jeans.
Help.
Im 5ft size 18 top and 18/20 bottoms. Ca throw a reasonable amount if money at this if i like it enough to wear anyway after my weeks training.
Smart Casual has vexed me. I do v casual or v smart. So please help.

I'm perplexed how they can dictate what you wear to training if you're going to wear a uniform to work. Could you wear the suit trousers with jumpers, Breton tops etc to stop them being too smart? I definitely wouldn't spend money unless it was for things I really wanted anyway or which would go on to form my work wardrobe.

Oh, and my work is smart/casual - a typical outfit for me at this time of year would be short-ish dress with opaques and flat ankle boots, or black skinny jeans with a blouse.

I sometimes have to do this for meetings or events where I'm never sure how everyone else will be dressed. I take it very literally i.e. something smart with something casual.

My go-to is a tailored jacket with either jeans or a tube skirt. I don't know if you could get away with black jeans? It works well because, if I find I'm overdressed, I can just take off the jacket. But if everyone else is smart, I keep the jacket on and, because I'm normally sitting at a table, the rest of the outfit is hidden anyway.

Or sometimes I wear a tailored pencil skirt or trousers with a sweatshirt or long sleeved Tee.

I like flat ankle boots for dressing an outfit down even further.

Thanka for your replies. I think ill buy some trousers and a few tops.
I woyld wear my black jeans and a smart bliuse and blazer but relyctant as tgeyve stressed no jeans. I will start wirg trousers and see what everyone else wears as the week goes on.