Thanks for all of your advice and thoughts everyone.
I have actually just realised that today is day 30, if you include the day that I collected the van (Sun 22nd Oct) as day 1.
It now has me thinking that I should put something in writing about rejecting the van before midnight - even just emailing to confirm that I am stating within the first 30 days that I am prepared to reject the van?
If I email them to formally reject the van - what will the next steps be? Ie. Is it automatically moving on to return/refund, or is there time for further investigation/negotiation about how the issues can be resolved?
The way I see it you've got nothing to lose by sending that E Mail immediately.
You can investigate how to progress the matter in the coming days but you've registered your intention within 30 days (If that becomes relevant) and the dealer may offer you a refund in their response, making it straight forward.
If they don't, you could report the matter to trading standards, but I don't think the dealer will want it to go that far, the adverse publicity from an unfavourable outcome would be extremely damaging to them.
Find your local Trading Standards office
Find a Trading Standards office to complain about illegal sales activity or to get business advice about trading legally
www.gov.uk