An anniversary party has one constraint the others do not: a good proportion of the guest list is elderly, and every decision follows from that.
It means parking close to the door rather than across a field, level access throughout, seating for everybody at once rather than standing room, and a room quiet enough at the edges that a conversation is possible while music plays. We have all of those, and they are worth asking any venue about before the deposit.
How they usually run
Four hours, often mid-afternoon into early evening so guests are not driving home late. Food is usually a buffet or family style rather than plated, because the timing is loose by design.
If it is a surprise, tell us. The lane is screened by trees, so arriving cars are not visible from the hall door — which is the detail that actually makes a surprise work.