Thank you for your question.
THe Firefox 8 twin door is NOT Defra approved, you will need to look at a Firefox 8 Cleanburn stove for one with Defra approval, https://www.directstoves.com/firefox-8-defra-approved-multifuel-stove.html
If it is the double door that has made you want this stove why not look at these Defra approved 8kW alternatives? - https://www.directstoves.com/stoves/double-door-multi-fuel-wood-burning-stoves/yes_1-7.1to8kw.html
Hope this helps?