Not sure what opinions others have, or what the delivery charge would be but I've purchased a Gates cam belt kit from this company.
https://www.autodoc.co.uk/gates/785477
I believe the company that made the genuine water pumps is BGA. A lot of the aftermarket water pumps have a standard o ring seal rather than a properly formed seal. Not sure that it makes them bad necessarily but I prefer to stick with the original design wherever possible unless it is fundamentally flawed.