Stick to your guns! If you explain to the insurance company what you have explained on here and tell them you will not accept liability, chances are, they will agree to fight.
Now, this generally means that either your insurance co or the other side will issue proceedings in the County Court (small Claims). The insurance company will normally instruct (and pay) solicitors on your behalf and will normally pay for a barrister to represent you at the hearing. PLEASE make sure you fill in the fullest statement you can. Unfortunately the statements that insurance companies provide for court are often woefully inadequate. Draw diagrams and write in precise detail (ie every single step) what you can REMEMBER doing and seeing. Ie "as I approached the roundabout, I was in x lane. My speed was y decreasing to z. I looked to my right and indicated blah blah".
It will often take a year or so to get to court so the earlier you make a statement (write it yourself now if the ins co have not asked for one) since the earlier you do it, the better (and prevent snooty opposing Counsel making comments at the hearing about the contemporaneity of your statement).
I disagree with Terambulan - it will only be dealt with in the Mags if the Police decide to take proceedings for driving without due care and attention or some other offence arising out of the accident. The appropriate forum for this claim (seeing as you are more concerned about liability and ncd, and there may be a personal injury issue) is the County Court.