Fiar play if you think the views are worth it. You be better driving down the road to dover and hitting swingate tower imo.
Go back through the posts and check the link I shared which tells you what is sent through those chims and their purpose. Some nasty shit.
Lived down the road from them my whole life and know the manager that used to run the maintenance team there. So from personal local knowledge I'm telling you that trying to climb them is a very silly idea when you don't know what is being pumped out of them at any given time. At the top you are most definately exposed to any harmful fumes or vapours.