This layout has been tested on a TADA68 purchased from kbdfans in March 2018. The physical key layout includes the "double height" iso Enter key and the "short" Left Shift along side the iso Backslash key. See this keyboard-layout-editor.com Gist
The Base Layer and Function layer defined here match the layout defined by the kbdfans keyboard layout tool found at http://123.57.250.164:3000/tada68
Please see the tada68 readme using the following command
make tada68:iso-uk:bin