Well, I was going to tell the garage to go ahead with their geometry check but then my wife very inconsiderately went into labour!

However, now the kid has been born, I can finally get round to doing it again. Apparently, the garage do a 4 wheel alignment check as per usual but also dangle plumb lines from the chassis and mark it all up. I don't really understand it but I guess all this will tell them where it is bent and if there is any vertical and/or lateral distortion. At least that's how I understand it!

Even if its not repairable, I'd still like to know the extent of the damage. I'll keep you posted.
Also, I got rid of the vibration at 60+mph by junking the aftermarket alloys and spigot rings and putting on some boggo standard bottletops.