Any advice on how to adjust the hand brake would be appreciated

First of all make sure the rear brake shoes are in proper adjustment with the drums - this may need taking the drums off to manually adjust them to just contact the drums.
Then adjust the cable by theaded adjuster under the van. You might find the adjustment ok after resetting the rear shoes...............

Under the van on mine there are three adjuster points....centre cable, + left and right cables......the shoes (left an right) should be self adjusting.
I never used to use the handbrake due to park facility on autobox. Now I always do after a cable corroded in its sheath and the drums had some self adjuster probs. Using the handbrake encourages the self adjusters to work properly........

That was my point chris - but better put!.....................self adjusters don't always work as they should and people then adjust the handbrake cable first - that then gives an ineffctive handbrake because it has to take up the shoe clearance first making the handbrake "feel" good but it's ineffective.

Suppose another point to clarify is how many clicks on the rachet should the handbrake cable pull.
My understanding on these vans is never less than 7...but around 9 is fine....
Any other views....?