So j saw my consultant today and he has said as long as my body doesn't go into ketosis then I'm ok to do any form or dieting where ketosis isn't key.
He has said that when i start treatment I will struggle with food anyway, but it's best not to commit to anything too religious in terms of diet as I need my body strength.
But he's happy for me to "diet" in a way that works best for me, till I have my op, and treatment so I'm happy with that.