The maritime force an independent Scotland might sustain

What submarines might an independent Scotland buy for a small navy?

Probably none at first; patrol vessels and perhaps uncrewed underwater systems would be more sustainable than conventional submarines.

Crew, budget, and support infrastructure are stronger constraints than the catalogue of available submarine designs. German conventional submarines might be considered eventually, but a new Scottish force would struggle to sustain them. A more likely underwater capability would use uncrewed vehicles alongside a patrol-ship fleet. The comparison with Ireland underlines the strategic consequence: a state without fighters or major combatants would still depend heavily on neighbouring British protection.