Would be a good idea to book in advance since it would avoid waiting in line. You won't be disappointed since it is well worth a visit with an excellent guide. Or, as another person has said, you could always wander in for lunch or a drink at the bar without paying for the tour.

Hi there, Besides our tour, we do welcome guests who are patronising our bar or our restaurant, Indigo. Our bar is open daily from 12 noon, and Indigo is open for lunch and dinner. Reservations can be made via our website. We highly value the privacy of guests staying within our boutique hotel, thus there are areas restricted to guests who are on not staying with us. Due to the high number of visitors who visit every day, our security does have to be cautious about entry in order to protect/preserve the heritage mansion, and the privacy of our hotel guests.