Thanks picklesgirl, Glitttergirrrl, return2curly and TaraVictoria!
I think I'm gonna go for a 'tamer' version of the style first. It will after all, grow back. Instead of having the sides as short 2cm, I will have them more like 4 or 5. At least that way if I don't like it, grow out will be quicker. And it will be just long enough to straighten from time to time and keep that flat down look without relaxing. I think.... If I was cutting all my hair this short I'd be more scared but keeping length elsewhere makes it less nerve racking.
If I don't like it I could take biotin suppliments to try and make it grow faster!