Firstly, best of luck with your interview! Inshallah all goes well! When it comes to your outfit, it's best to keep things simple and neat; no crazy prints or too many embellishments. This applies to your scarf especially.
I love this beautiful skirt suit from Next. All their skirts also come in a long option too:
You can't go wrong with a basic black skirt, and smart blazer:
Or if you don't want to wear a jacket, simply find a smart long-sleeved shirt or jumper:
It can be difficult to find long jackets to wear over trousers, but Littlewoods does a great one which comes in 3 different colours:
A look I find is slightly more relaxed, is to wear a long sleeved dress over wide leg trousers: