Just bought this months copy of 'Retro Gamer' magazine and there is an eight page interview with the twins. It covers the early years, the 'Dizzy' era and 'Blitz Games'.
If you don't buy the magazine then no problems as they are making the whole interview available for download as a podcast. The first part is currently available which is mainly about the early years and lasts for about twenty minutes. I followed the podcast interview with the magazine at the relevant sections and the podcast goes into much more detail.
Download or stream here
https://www.retrogamer.net/podcasts/RG_04_Podcast.mp3
The interview starts about 12 mins 45 secs into the recording as there is other stuff too.
The making of 'Dizzy' will be in the next podcast. I will post again when it is availabe or you can buy the magazine to read an edited version now.
edit : I should warn you it's about 60 megs and the download speed is capped, but not to the extent where it takes forever.