I have seen tube heaters discussed many times for brew fridges but if you only need heat for a brewing cabinet these have a thermostat.
https://www.amazon.co.uk/d/Lighting/Dimplex-Ecot1ft-40w-1ft-Thermostatic-Tubular-Heater/B00NT0X8K2
Dimplex Ecot1ft 40w, 1ft Thermostatic Tubular Heater [Energy Class A]
Tubular Heater with Inbuilt Stat
Manufactured by Glen Dimplex Creda Group (GDC)
Packaging may vary (ECO1FT/SHTTH1)
Supplied Complete with Brackets, Flex & UK 3 Pin Plug
White with Beige Coloured Ends
https://www.amazon.co.uk/d/Lighting/Dimplex-Ecot1ft-40w-1ft-Thermostatic-Tubular-Heater/B00NT0X8K2