I bumped my Golf a few years ago (slid in the snow into a sign post) and it was repaired at Clarke's in Kibworth, at the insurer's request. It's only a few miles from me so I didn't argue.
The
service was a bit abrupt/unfriendly, albeit professional, but they certainly did an excellent job with the car. For bodyshop type stuff like matching paint colours and replacing painted parts, I would think they are a good bet. I assume your new bumper will need spraying?
I'd guess that they're not cheap though.
Here's their website:
http://www.clarkesltd.co.uk/default.aspx