Cold workshop; been there done it for many years; good outdoor gear the best as it is also comfortable; helly hansen underwear, ron hill type leggings, fleecy shirt of some sort, fleece top, balaclava, fingerless gloves, two pairs of socks one thick one thin, walking boots or trainers, boiler suit, and body warmer jerkin on top. Radiant heat best. Oil filled electric rad is quite radiant over a wider area if you sit near it - it can warm your back, better if painted black (radiator not your back). Then dash back inside every half hour for a nice cup of tea.
cheers
Jacob