Do they have any free seating or you have to book a table?

Tables are mostly on a "First Come". You can call & reserve a table for a large crowd.

There is no need for reservations. FCFS

Unless you come on a popular weekend evening, seating outside should be no issue. It's a very large outdoor garden. If you have a large party on a weekend (8 or more people) or want to sit inside (few spots) you may want to call ahead to double check they aren't at capacity.