"Successful bids
If you bid successfully, you’ve entered a contract with the seller. You’ll be given a bidding slip and asked to supply the name of the buyer and solicitor involved. You’ll then have to pay a deposit of 10% of the sale price, or the auctioneer’s minimum deposit, before the auctioneer’s clerk can prepare the contract.
You must sign the contract before leaving the auction room, and give a copy to your solicitor. The auctioneer will ensure the seller’s solicitor receives a copy of the contract. Completion usually takes 28 days, though sometimes special conditions require a faster completion."