In a word, yes. If your bid is successful on the day, you must pay a deposit of 10 percent of the purchase price immediately.
The auctioneers will also ask for proof of funds to pay the balance by completion, usually only 28 days later. That means you must ensure all your finance is in place before making any bid.
Cash buyers will have to demonstrate they have the money in place, and if you're buying with a mortgage, you must arrange an agreement in principle before making any bid.
Lenders will only make a definite offer once you have bid on a specific property. Your auction conveyancing solicitor will liaise with the lender before the auction to ensure the finance is secure.