How do I batch invoices to do my VAT returns for March and April

Welcome to the Community, @dennis30.

At this time, there isn't an option to create invoices by batch. You can consider creating them one at time. Or add all the transactions in one invoice. 

Here's how:

1. Click the + New button, then select Invoice.
2. Select the appropriate customer from the drop-down.
3. Choose each item in the Product/Service column.
4. Fill out the necessary information.
5. Click Save and close.

I'm adding this article for more details: Create invoices in QuickBooks Online.

Once you receive the payment, you can read this article to learn how to record it: Record invoice payments in QuickBooks Online.

Please keep in touch if there's anything else I can do to help you succeed with QuickBooks. I've got your back. Have a great day and keep safe.