Welcome to the Community, Phil. Before you can link QuickBooks directly to HMRC, you must first "opt-in" to Making Tax Digital for Income Tax (MTD for IT) via the HMRC website. HMRC must recognise you as a registered taxpayer for MTD for IT.
Once that's sorted, go to the Gear icon in the top-right corner and select Account and settings > Company. Ensure your Business type is set to either Sole Trader or Landlord. The Taxes tab won't appear on the left-hand menu until one of these is selected. Check out the screenshots below for reference.


For further assistance with setting up MTD, please refer to this article: Set up Making Tax Digital for Income Tax in QuickBooks.
If you have any other questions or concerns, feel free to leave a message in the thread.