Paul_N - Welcome to my build thread.
I actually went to great lengths to plumb in a micro heater that would direct hot air into the footwells.
( These photos were taken looking up from the cockpit floor. )
I originally fitted a 3 speed switch, which then "blew".
So it now has a 3 speed dial that works on a simple on/off basis at position "I".
Unfortunately, all this work has resulted in something that makes a lot of noise, but no heat.
However, this may be linked to the fact my temperature gauge reads very low when it is cold out.
So I've bought a new thermostat value to see if that will fix two problems for the price of one, but haven't fitted it yet.
I certainly think it is a good idea to have some hot air around your feet, especially when it is barely above freezing outside!
Good luck, Paul.
PS
What are you building and do you have a build thread anywhere?