Have you tried the first 2 things off the list from the 'reluctant starting' link above?
Might be useful to get - at least - get battery and starter motor off the list before giving the van 'the bullet'.
Don't get even - get methodical!
'Pop under the driverside rear wheel arch and check the signal wire to the starter motor is connected to the spade connector on the solenoid.
1. Turn key to first position- red dash lights not coming on. Battery flat or electrical connection faulty, i.e. battery leads loose or fuse loose/blown
2. Turn key to second position (start)- no "click" and starter not turning over, See 1, starter motor seized or electrical connection to starter motor loose.
If connections are secure and not corroded give starter motor a couple of hits with hammer or similar to "unstick" it. Suspect worn starter motor bush.'
Worth a try?
Madame Rose - at the end of Southend pier - she say - 'perserverance furthers' -

Owner of a red T25 fixed hi top campervan - colour - spikey red - petrol - water cooled - 1.9 dg engine rhd - 1990 g reg n still going strong!-