Catching up on my data entry for the previous financial year. Do I need to back date my invoices or as long as I enter the date the funds were received will this be ok?

Keeping the data accurate is necessary in a business, Tania.

Entering back-dated transactions such as invoices and received payments will change your current balances and reports. I'd recommend reaching out to your accountant to verify if the dates you want to use are correct. Then, you can continue entering the said transactions.

Then you can already close your books afterwards.

I'll help you more if you need anything else.