Code of Practice COP9 is used for cases of suspected fraud or deliberate errors. COP8 is used for cases where fraud is not suspected – the problem is more likely to be a technical issue. Both types of investigation may end in civil (rather than criminal) settlements.
This is an extremely serious level of investigation which will no doubt involve a number of very formal meetings.
Your defence team would be made up of two partners from our office together with relevant tax specialists and no doubt some legal representation.