[Closed] Mudguards on a Charge Plug.

So, as a direct result of that 'Can a brown bike ever look good' thread, I've just bought myself a Charge Plug 2.
Wasn't even aware that I needed it until I saw that thread, but anyhow...

Its got 42c tyres on, which actually measure 42mm & I've reserved some 45mm Longhorn mudguards for collection at Halfords. Will these be wide enough?

I've not owned a road bike since I was a teenager, about 30yrs, so have no experience or expertise in these things. What is the tyre size to mudguard width ratio, if there is one?
Has anybody fitted mudguards to a 2016 Plug and if so, what did width did you go for, how's it working out?

Thanks.