The title may be a reference (like "The Beach At Redpoint") to a real place in Scotland; "Buckie High" (now Buckie Community High School) was the name of the high school that the band attended. Buckie is a small fishing town in the county of Moray. Scottish schools are like their American Counterparts known as High Schools (Secondary in England). Coincidentally, there is a café near Buckie High School called Sandisons.[1]
Alternatively, the song title could be a reference to 'Buckfast', colloquially "Buckie", a tonic wine infamous in Scotland for its potency and extremely high caffeine content. 'High' in this context would be a refrence to being intoxicated.[2]
Quoting Gaby Ghazi: when I was a teenager having just finished school and turned 18, we made a bucket bong called Buckie and we filled it from the sea and smoked on the beach. I then went home a few days later and discovered the Old Tunes, and Buckie High specifically [...][3]