If you're not used to tiller steering, you automatically put the tiller the way you want to go, especially if you're already a bit flustered. Hence the "going into the brickwork" situation, of course. It brings back memories.... The first time we hired, the intructor only wanted one of us on deck, so I duly went inside and startet to unpack, and left my husband to it. 5 minutes later I was called out. My husband simply hadn't been able to get the hang of it, so I was asked to take over. Needless to say, the next day when we were on our own and all was calm, he picked it up quite easily.
When we hired (from Wyvern and Canal Cruising), we always had a thorough handover, which included the instructor accompagnying us through the first lock and showing us how to work it. Even when we were returning customers.