I've been to four different pub gardens after four different walks and:
1. I didn't book a time slot with any of them
2. I didn't fill out any details on arrival
3. I didn't pre-order drinks via an app.
In three of the pub gardens our orders were taken via table service and payment was taken by a remote card reader. Drinks were delivered at the table.
in the remaining case I went to where a till was i.e. a few yards away
It was a far more pleasurable experience in each case than standing indoors at a bar and trying to work out who should be served first - and then transporting the drinks outside without spilling them.
Cheer up you grumpy so-and-so