On that Facet pump: That's what I originally had in my car when I first built it. It simply drove me nuts. It has that aggravating clatter going on all the time and even mounting it in rubber didn't really help all that much.
If you have your heart set on a Facet (they do move the fuel to the carbs well, after all) Aircooled.net has fuel pump rubber isolators that, they say, effectively isolate the pump from ringing the frame. Look Here> http://vwparts.aircooled.net/category-s/173.htm Scroll about halfway down. You can probably find something locally at a DIY store.
Or you can save yourself the aggravation and get a rotary pump from CB Performance, Carter or Aircooled - There must be rotaries for sale in the UK, as a lot of larger displacement VW sedans are zipping around over there.