I sympathise with your situation King_o. The other driver was definitely in the wrong in my opinion but these days with insurance claims without an independent witness or camera evidence they'll probably treat as 'knock for knock'. Although maybe the fact he's admitted being in the wrong lane to complete a full circle of the roundabout it could be admission of liability...
Got the latest copy of the Highway Code (they gave it to us on our BikeSafe course lol) & found this quote from Rule 186 (Roundabouts section):
'When taking an exit to the right or going full circle, unless signs or markings indicate otherwise:
signal right and approach in the right hand lane
keep to the right on the roundabout until you need to change lanes to exit the roundabout
'
........
Like the other guys say it's SO fortunate you weren't on a bike and had the protection of a 'cage' but regarding your immediate problem of the claim try contacting this guy:
Tim Kelly at MotorClaimGuru Ltd
www.motorclaimguru.co.uk