I was hoping somebody could give me advice on a bike route from Gouda to Tiel i.e. fastest, best, overall length etc.

Cheers!

Try the North Sea Cycling Route. It is a bit difficult to navigate, but if you go to the Netherlands page, you can get some suggested routes.

It would appear that the site only lists routes relevant to the North Sea unless I am not finding the correct link. Any suggestions?

Hi there, you can follow the cycling route 13 to Schoonhoven than just follow the signs to Leerdam, from there route 37 to Tiel, its the quickest and easyest way.
You can't get lost, at every junction there is a map showing you the next section of the route. You really don't even need to bring a map.
Just ask anyone in Leerdam as to where you can get on route 13 (fiets pad derteen naar Leerdam) and they should show you the way.
Cheers

Cheers Xilios!