Hey there, Louise2.
In QuickBooks Online, you can only file the VAT return and payroll. For your end of year accounts, you'll have to do it in the HMRC website.
You can send feedback to have that feature added in the next updates. The more requests a feature has, the more likely it will be added by our software engineers. You can do that by clicking the Gear icon, then choosing Feedback.
If you have other questions, you can always visit the Community.