Hi there, WBJ Designs!
If both accounts are connected to your QuickBooks Self-Employed, your transfers will show as an expense (money out) in the Metro account and an income (money in) in the Lloyds account. All you want to do is choose the Business type and categorise them as Transfers. Here's an article for additional reference: Transfers between accounts in QuickBooks Self-Employed.
If the accounts are not connected, you can manually add them to each account and categorise as Transfer. Please note that money in has no sign on the amount while money out has a negative sign on the amount.
With regards to adding personal funds for your business bills, you can also create money in with a Transfer category same as above. You will follow then same process I explained above. However, you'll want to select the Personal type so they will be included to your tax estimates. When you pay yourself back, create a money out transaction with a Transfer category and a Personal type.
If you have other questions, you can always go back to this thread.