Can I add a Cash in Hand account and how?

Yes, you can, @Spriggangoodjob.

I'd be glad to walk you through the steps on how to add your cash account in your QuickBooks Self-Employed (QBSE). Here's how:

1. Go to the Profile ⚙ icon and then select Bank accounts.
2. From the search box, enter the name or URL of your bank then select Continue. Or select Connect another If you've already connected an account before.
3. Enter the sign-in info you use for your bank's website.
4. Then select Connect.

You can also check out this article for more details about the process: Connect bank and credit card accounts to QuickBooks Self-Employed.

Once done, you'll want to categorise your transactions to ensure your accounts are well organised.

In case you need more help connecting and categorising your account, you're always welcome to tag me in your reply. It's always my pleasure to help and keep you on the right track. Keep safe and have a good one!