I think you'll need to find a Novopen 3, which you would have to be lucky to find second hand.
Also, have a good look if the penmate that's still available is actually for insulin, I found them on the internet but they seem to be for a growth hormone.
You could always contact NovoNordisk directly with your questions:
https://www.novonordisk.co.uk/contact-us.html
If it doesn't work out with the penmate, you could have a look at safety needles where you don't see the needle. They are made by different companies and like the regular penneedles fit all insulin pens.
Or you could have a look at the Tickleflex, might be worth a try as well:
https://shop.diabetes.org.uk/products/tickleflex-insulin-injection-aid