Abbey, have a bit more confidence, we all make awful fashion and style mistakes when we are young. One thing I would suggest is working out what suits your shape and colouring. A colour consultant would be really helpful but you would need to save up. Or maybe it's something you could ask for , for your birthday.
These are the best known and in the long run you will save money because housing make mistakes when you shop.
https://www.colourmebeautiful.co.uk/
It's fine. Not too short. I wore far shorter dresses in the 60/70s too. If you are young and have nice legs then go with it. It's a very respectable dress.
The days are long gone when working clothes had to be boring. I'm surprised though that they haven't supplied you with a uniform.
I wore hotpants to work as did a lot of us. And noone complained. Worked at the Open University in its early years. Lots of young staff. They were great days.
PP I was Secretary to the director of publishing who was also translator of the Tintin books and an ex Bletchley Park codebreaker.
I never did a degree. It was a really fun job and the social life was great too! Lots of interaction with bbc staff as well.