The bar top is rarely the part that makes the plan fail. Door swing, standing room, storage and the route between seats consume more floor space than a sketch suggests.
Tape the layout at full size
Mark the internal dimensions, counter depth, stools and open doors on the ground. Walk through with someone seated. Keep heavy equipment and any electrical needs in the initial building brief.
Keep the shell maintainable
Do not block every wall with fixed cabinetry before planning inspection and treatment access. Condensation and spills add to the moisture a seasonal timber building must manage.
The next revision will add a compact layout diagram and one natural link to the Garden Bar Guide when that target is live.