I did the exact same thing with my car last December in the snow. I'd even say my impact wasn't even 5mph, but the car just stopped dead against the curb.
The damage - visually, just a scuffed alloy and the top of the wheel was leaning in too much (like too much camber). But when I took it in, VW dealer said I had damaged the hub, track rod, track rod ends and bearing. With labour, the total was over £700. Then I got the wheel re-furbed and ended up taking it twice to another garage to get the tracking checked and re-checked because I wasn't happy. Overall damage closer to £1000!
So, I don't mean to be the bearer of bad news, but this was just my experience. I was told that if it was a lesser car like a polo, the damage may well have just been the tracking - but the GTi has much more expensive and intricate parts.
I think you're doing the right thing not driving it until fixed - there obviously is something seriously bent in the suspension!
Good luck