Each country has its own taxation regulations. Allow me to offer my help with filing taxes with HMRC, ayhtida.
Please know that every localized version is customized to comply with the tax regulations and filing processes relevant to that jurisdiction. Can you also tell us if you're using a USA version of QuickBooks Online?
If so, this is the reason why you can't see VAT or any options to file taxes to HMRC. You'll want to create an account for QBO UK so you can start tracking and filing VAT.
To get started, you can sign up for a UK QuickBooks Online account here: https://quickbooks.intuit.com/uk/
If you already have a UK account, follow these articles as your guide on setting up VAT, managing your payments, and ultimately filing your VAT return directly within QuickBooks:
I'm also sharing these articles just in case you need more VAT-related resources and information:
As you begin tracking VAT and managing those transactions in the UK version of QuickBooks Online, remember that you're not alone. The QuickBooks Community is a great resource if any questions come up. Feel free to reach out there for support anytime.
