Nomad

Hi all and happy bank holiday weekend to you. I am trying to price up an extension for my ground flat, see the attached diagram. A 20m2 extension will be our new kitchen, diner. I've got a SIP built garden office which I have been pretty pleased with, but am uncertain of for a long term sustainable project. So am leaning towards ICF for speed of build vs a timber frame. We will be living through this, so something that can be erected rapidly would be favourable. What material would you use?