Proof of Goods Expenses and Tax Settlement Clarification

Hey guys. I’m going to do some retail arbitrage as a Ltd company and I am a bit confused. Is it enough to keep the store receipts from checkout as proof of goods expenses for a tax settlement, or do I need to ask the store team for an invoice in the name of my company? I’m not registered with VAT yet.

Receipt is officially stated as legal prove of purchase, that’s legit legal paperwork for any legal activity to be confirmed.