Functional bikes. Not Porn not Anti

Gearing advise, please.
My rawland 29" is currently running SS, but I'm looking to get a 1x10 drivetrain. Just unsure what size cassette and chainring to go for.
It's 42x18 now and mostly fine if a bit heavy at times.
Usage will be Copenhagen commuting with the occasional off road detour and sometimes with rather heavy load too.
I'm propably going to get a Wolftooth 110 bcd ring.

Here's a retrograde idea, just get a nos Suntour Perfect (or whatever) 5 speed cogset (14-34) and spin that on to your current hub. Everything remains at 120mm and you get a great range. Comfort with friction shifting required though.