I find it annoying that that voice instructions are too long winded e.g if being directed to follow the B3227 this would be stated as "B three thousand two hundred and twenty seven" instead of " B three two two seven".

Is there any way of changing this via the menu ?

No. It's the way the system works. Just the same on my BMWs - which is one reason I gave up using it. That and the 30-pages of voice commands to be remembered!

Thanks for your reply Felis.

I find it annoying that that voice instructions are too long winded...

It uses mostly text-to-speech, hence long numbers and some dubious pronunciations of place names.

You can curtail announcements in the Nav>Settings>Nav.announcements by selecting "Brief".