To answer some of your questions
Do the portions keep hunger at bay (obviously I expect to be hungry before meals but not to the point where I feel really deprived all the time)?
-YES! you eat loads, to the point that some people struggle with the amount of food. 3 meals a day plus 2 snacks. You wont feel at all like you are on a diet and will probably question how you can loose weight and tone up eating all the time.
I know you can pay for one cycle at a time. Could you pay for cycle 1 and then stop if it wasn't working out?
-No you have to pay regardless, the money comes out your account each month regardless if you continue or not.
Has anyone combined the diet with their own HIIT workouts? I do T25/run 5 times a week. I tried one of his YouTube videos and I prefer t25.
-You can do your own exercise, you would need to state this in your questionaire so that you macros can be calculated according to your exercise. you dont have to do the youtube HIIT, you can do any HIIT you want, I did treadmill sprints, some people do crossfit, some do different classes etc, you can decide. C1 you only do HIIT 4-5 times a week, C2 and C3 its HIIT alongside weight training.
Is anyone doing it alongside a partner who isn't? How do you manage that?
-My DH didnt do the plan but ate exactly what I did, I sometimes added in carbs into his food but normally it was just the same, he is also very active and really liked the food - in fact people noticed a difference in his body shape before they noticed mine!
Finally, as I am going on hol at the end of the month I prob wouldn't get my plan thru in time so has anyone tried just doing his recipes etc from Facebook with any success?
-The recipes on IG and facebook are nothing like the recipes in the plan, if you are going on holiday at the end of month i would suggest waiting till you come back to start. The plan takes about 10 days to come through and you can then start whenever you want, there is no time frame on it.