Really bad luck Cyber.
I don't want to upset you, but I think you will have difficulty getting anything out of the council. Below is the tale of a similar stack we had on a chaingang last year. We spoke to BC and they advised that my mate might be able to claim but as I didn't actually hit the pothole, I'd only have a chance if I could ride on his coat tails (or launch proceedings against him! - I hasten to add they were stating the law not recommending this course of action). Fortunately I had little serious damage but my clubmate was not quite so fortunate. The incident happened in May 2010 and my mate is still trying to prove his case - various visits to specialists to prove his shoulder does actually hurt etc. The council won't accept liability as the pot hole, according to them, is less than 100mm deep (and, incidentally, it's still there).
We were coming to the end of one of the faster sections, it's under trees and always a bit damp on the road. THere was a pothole filled with water, so not really visible, right in what you would call primary position (it's a wide-ish country lane). I was near the back as the group went round the bend. We're all experienced cyclists who race and the hole was called but at 30mph the whip end of the group is always going to cut the corner and the guy in front of me hit the pot hole and went straight over his handlebars. I had no option but to go over him. Amazingly, no one else went down.
Result: I needed a wheel true and had a couple of scuffs on the saddle and levers. My mate wrote off a Wilier Cento Uno. He skinned his knees and elbows down to the fat and got the pleasure of my chain wheel scarring his face. I got a broken finger and very bad bruising to my shoulder. A year on, we were both physically fine after about a month and were back riding and I was racing but it could have been much worse. My mate still has trouble with his shoulder though and is definitely less keen on his riding.
Riding in a group is difficult and people don't always shout out for cars and potholes. The chaingang tends to be good for this - the riders mostly race so they know how important it is and how to take safe action even at high speed. Clubruns can be a bit more inconsistent. I've turned into one of those annoying blokes who shouts at people for not shouting - but then I think that is another thing that bunch riding gives you.
I hope all resolves itself satisfactorily and really hope you get somewhere with this.