Whats wrong with my car?

I have a citroen saxo, 1 litre engine and i skidded on the frosty road and hit and mounted the curb, it made a loud bang like something broke, the outside looked fine but when i drove home the steering wheel was shaking and pulling? what do you think i have done to the car? how long will it take to fix and how much will it cost?

Impossible to say without seeing it. You’ll need to take it to a tire and alignment shop. It could be a simple as a bent rim, or as bad as a broke suspension member. If it feels totally unsafe and impossible to drive straight, have it towed.

Have this car towed. Do not drive it.

You clearly and badly damaged something in the chassis (impossible to know without looking) and the items you could have damaged are critical to control. You could suddenly have the ball joint or the tie rod end come apart and end up slammed into the front grill of an oncoming tractor trailor truck.