George Lennox (Robert Carlyle) takes Carla (Oyanka Cabezas) up a hill with a view of Loch Lomond and the surrounding mountains where they have a champagne picnic. Filmed roughly halfway up Conic Hill on the east side of Loch Lomond near Balmaha.
From Drymen on the A811 between Balloch and Stirling take the B837 to Balmaha and park in the carpark on the right of the road. Go up to the top of the carpark and through a gate into the woods and turn right onto a track. After a couple of hundred meters take the first path on the left and continue along this eventually coming out from the woods onto open moorland.
Continue along this path for another couple of hundred meters and you will come to a junction where the path coming up a ridge from the road joins the path which continues to the top of Conic Hill. The filming location for the view over the islands seen in Carla's Song was slightly before this junction looking down the valley between the ridge on the right (Druim nam Bruaich) and the craggy wooded top of Tom nan Oisgean on the left.
If you have the time you should continue on to the top of Conic Hill with it's wonderful views over Loch Lomond. Alternatively return by the route you came up, or via the path going down the ridge to the B837 where you should turn left and follow the narrow road back to the car park where you started.