Thanks Naomi but I'm happy in my choice -- or at least as happy as anyone can be when they feel it's better to vote tactically rather than honestly.
While an SNP Labour coalition may be inevitable, I feel the UK's interests are better-served by ensuring that it is as much Labour as possible. The more MPs the SNP have the stronger their position is. Better to have the split be about 300-30 in favour of Labour, say, rather than 285-45. Indeed, in the former case the Lib Dems might be able to form a coalition with Labour, so it wouldn't matter.
No, a vote for Labour it is. I made my mind up on that months ago, and I think it's the best decision I can make in this position.
If I were south of the border, I might actually consider policies as more important, but a tactical vote it is and I think it's the right decision.