Haddington is generally a very safe place to travel even for solo female travelers. Like anywhere in the world, there is always a small level of risk but overall Haddington has low crime rates compared to other parts of the UK. It's a small, friendly town where people often look out for each other. That being said, the usual travel precautions should still be taken. Make sure you research in advance and stay aware of your surroundings especially at night.