which boiler should I choose 35kw glow worm or a vaillant 32kw

Hi there, in my honest opinion vaillant is as good as it gets. I'm not sure about glow worm. I've not had much experience of working with them. The KW rating is only hot water output (assuming this is a combination boiler). So 32KW is more than adequate for a modest home. If your home is large with multiple bathrooms I would consider an un vented cylinder and system boiler.