You can make an out of time appeal and say that you have just bought the car and the PCN is the responsibility of the previous keeper to name the driver. It you know the PCN number then this article explains the procedure for making an appeal: http://www.dealingwithbailiffs.co.uk/St ... ailiff.htm
If the bailiff is concealing the PCN number from you then charge everything to the council, and the town hall can settle its costs with the bailiff company.
You don't need to provide insurance documents to a bailiff because you have no contract with them to do anything. It is a tort and if the bailiff commits a wrongful action against you then the council whom the bailiff is contracted by is liable for damages under the Torts (Interference with Goods) Act 1977 and you bill the council , and if needed, reclaim it on a Form N1.
The insurance policy terms and in whose name it is in has no bearing on determining who is liable for traffic debts of the insured vehicle or deciding whether the vehicle has business use.
Bailiffs cannot use wheel clamps full stop. The regulations do not provide for it but bailiffs feel that clamping is a substitute for what is called 'closed possession'. If you are clamped and its done by an unregulated private company then you have the right to remove the clamp using bolt cutters: http://www.dealingwithbailiffs.co.uk/cl ... rights.htm
The debtor is the person named on the warrant and its only enforceable against that person. The bailiff ought to know this, but if he continues enforcement against you, then he is being dishonest and you have a right to make a complaint against his fitness to continue trading as a bailiff. This is called making a form 4 complaint: http://www.dealingwithbailiffs.co.uk/Ba ... plaint.htm