Depends what you use at the local fishery , a lot of guys prefer to fish traditionals at fishery's , Sandy with his Spiders etc
For a wild loch , If there was a hatch I would fish dries and try to match it. You don't need to be an entomologist , if there is something small and black hatching , fish a small black dry.
If there is no surface activity , traditaional Scottish wets , Grennewells , Black Pennel , Bibio , Kate Mclaren , Soldier Palmer, Invicta, Peter Ross are some of my favourites.
Beannie has a lot of freshwater shrimps so some shrimp aptterns would not go amiss , its a shallow loch so a floater or at most a sink tip will suffice.
Jim