I lived near Watford and worked from home for years, and in general rated my clients (at least compared with those I've dealt with in Lancashire) pretty highly. I was a couple of minutes from a junction of the M25, so most were driving to me and as there was on-street parking it was no problem. Central Watford may be a little different, but Watford Junction is a busy station for London commuters. I, personally, liked the convenience of being so near London and yet also being near some green space and having more a community feel, and the location of my house meant nosey neighbours weren't a problem either.
I was definitely busiest during the day, but did do quite a few evening bookings.