Depends what assistance could be given.
Because old diesels stink everywhere. I'm in Penrith at the moment and they utterly stink here. They harm my health, they harm children's health.
The air in London is now nicer to breathe than in Penrith. Let that sink in, that's big.
If a newer van isn't affordable, consider an older petrol estate car instead. 10+ year old models often comply. Or if this is just a car, just get a petrol car of similar value (I would expect a national ULEZ to include a scrappage scheme based on values before announcement as resale won't be possible).
You're massively over exaggerating; what do you mean by old diesels? This report (I hope the URL copies correctly, if not will try again, I have just tried it and it does appear to work)
Concawe
https://www.concawe.eu › R...PDF
A comparison of real driving emissions from Euro 6 diesel passenger cars ...
suggests that actual real life emissions from a post 2015 diesel is about the same as an EV as tyres contributed more to particulates and even NOx were negligible. I didn't choose this to be biased, it was the first I clicked on. I also hope I've interpreted the information correctly so apologies in advance if someone finds a flaw in what I've said.
Pre 2015 diesels were worse in both respects but they still don't 'stink'. I had a 2007 diesel car, which definitely had a particulate filter so most of these were removed.
Think you need to be a bit more realistic and not jump on demonising diesel bandwagon like lots of people including our politicians. I'm not claiming they're putting out emissions that are as clean as the air they take in but they are also not the big problem some people will have you believe.
We should be aiming to have as much traffic on public transport and not go down the road of kick out ICE cars and bring in EVs. Less traffic is a better option but, in reality, that will probably never happen?
Your internal combustion engine is typically only warranted for 3 years.
I have never had a car where the engine doesn't last 8 years, even second hand ones!