My customers receive my invoices but can only see the amount, when they click on it it shows them no further information so then they are having to ask me for ways to pay. Surely this should be within the invoice?

I can provide you with some information about invoices in QuickBooks Self-Employed (QBSE), @James Lance.

When creating your invoice, you can add the steps or instructions on how your customers will process the payment in the Payment details box. Add a mark on the Save payment details for future invoices checkbox to save the information you've added to your future invoices. Check the screenshot below:

You can let them click on the View Invoice button on the email they've received to see the details of the invoice that you've sent to them. 

Here's their view when they click the button that I've mentioned above. They can pick on that View invoice button to get a PDF copy of the invoice.

Check this article for more information about invoices in QBSE: Create invoices in QuickBooks Self-Employed.

When you received the payment from them, you can follow the steps provided in this article on how to manually add transactions in QuickBooks Self-Employed.

Let me know if you need further help with your invoices and or anything else. I'm always here to answer them for you. Take care and have a great rest of the day!