Dred,
Since you appear to be in the UK and are talking KM, is this van on the continent? I'm not too familiar with vans, but 66KM (aka 40,000 miles) doesn't sound very high for a 1998 model.
Remember that spare parts will be an issue in the UK, although the days of the internet and eBay can work wonders.
Maybe some of our Great West owners will chime in, although I only personally know of one such couple. They really enjoyed the van and had some great times in it.
It's been a long time since we lived in the UK, but is the seller obligated to ensure the vehicle passes an MOT, or is that up to the buyer. If the latter, it's caveat emptor. Depending where on the continent, it probably escaped the evils of salt on the roads.