I am not sure what a "float n fly" technique is. In the winter most fly hatches slow down or stop with the big exception of midges. while i have had a few amazing days on top with midge dries i still catch the majority of fish during "midge" days under an indicator on midge pupa. In fact during winter nymphing under an indicator or fishing streamers is the norm.
I suggest you join a local fly fishing club or find a fishing buddy to help you find some public water that has fish and maybe learn a new technique or two.