Interesting post as I had to look at this carefully when I started up my business from home.
Firstly, if you ignore it, it will get worse and is likely to make you look guilty so talk to them, be polite and be open, no hiding vans round the corner on the day of the inspection.
From what I learnt (you can look at your local councils web page) , councils to determine there has been a change of use to a property will be looking for: -
1) No excessive visits from your customers or deliveries or pickups.
2) No blocked roads with excessive customer parking of vehicles interrupting neighbours access.
3) No excessive noise from visitors or running the business - milling in a residential back garden for instance!
4) No excessive smells from running the business
5) No advertising boards outside the property
6) No change of structure to the house or land to accommodate the business - having a four pillar hydraulic ramp, inspection pit and cars parked up and down the street will be a red rag!!
7) The time that anything happens for - a couple of deliveries a day is pretty average for an eBay fiend or a lady that likes mail order clothes..........etc
Getting on with your neighbours helps a lot but it is often not them but the neighbours neighbours or even people further away.
In your case, I would say you are OK if your wagons are only parked on your drive with nothing else going on. If you are maintaining chippers, taking the vans apart, having a load of workers coming and going using up the parking spaces along the road, it may be viewed differently. Your business yard will be a big help in your defence.
It would be good if both wagons were parked up the side of the house but guess that can't be done.
You could phone the council, express to them your current usage and then see if they still need to come out and see you. They may just need a letter from you stating your use of the property and it may go away if you don't deviate from it.