The HMRC are likely be to interested in the chart of accounts relating to;

Profit and Loss
Accounts > Profit and Loss > Click to drill down into each of the income and expense accounts listed in the P&L report. These show all sales made, and expenses incurred, so are the most important items for tax reasons.

Each of the Income or Expense account can be individually found in Accounts > Chart of Accounts, and can be exported or printed out.

Fixed Assets:
Accounts > Chart of Accounts > Drill down into the "Asset" type accounts, if you have configured any.

Since Fixed Assets are not shown in the P&L and may have also given an INPUT to the VAT account, these may also need to be printed out.

Tax Account (this a VAT account)
Go to Accounts > Chart of Accounts > Tax Account

These are inputs and outputs that affect the VAT account. I.e. if you made a purchase and the VAT of that purchase was £10, the £10 can be seen on this report.