EUROSPRINTER
If you are having trouble uploading your reg document on the Crit' Air application form there is a free program available to download on line it is called PIXresizer
it is fairly easy to use & you have a choice of sizes to select from 75% 50% 33% 25% this is what I used I first scanned the reg document as a JPEG file and then loaded it into the PIXresizer selected 33% then clicked on save picture Job done ! The picture I have attached of the classes of permits available started out as 874 KB after resizing it is now 160 KB.
If you do get a Crit' Air sticker be very careful where & how you fix it to your windscreen it has to be on the lower RHS of the screen as viewed from the inside of the van (drivers side on a RH drive vehicle) placed anywhere else and you will be fined for "not having one" also take care fitting it as when you offer it up to the screen it is very very sticky and if you try to remove & refit it part of the sticker will stay on the screen with the word VOID on it and you will have to apply and pay for another one.
The Low Emission Zones appear to be breeding, and can change on almost a daily basis, the advise is to download an app for a smart phone and check on a daily basis the air pollution level of the area you are intending going to