I buy cars to break for parts and sell the parts. I take cash out of the bank to buy the cars. What category will this transaction go into when sorting out transactions?

I have been in a similar situation before and was advised by my accountant to list it as a running cost in my business expenses. What made me nervous was that I didn't always get receipts for things purchased with cash, so I didn't think I could list them all. My accountant sent me this https://www.pie.tax/tax-pible/maximising-tax-claims-without-receipts really helpful