I expect most of the usual suspects would be able to help you with fitting - Autolink, 5 Speed, Sam Goodwin, etc, etc.Give them a bell.
As for supply, EverythingMX5 also claim to sell and fit Hard Dog
Phil @ P5 is a seriously busy man. May be worth sending him an email with the subject 'Serious enquiry about Hard Dog rollbars' or some such. He's a nice chap when you do finally get to speak to him - however he is that busy that I suspect if you're after fitting as well it might be best to try and sort out an alternative.
There's also TR Lane if it's a roll bar you're after.