I'm not sure why you would think it's the menopause? If you've gained weight, then you've gained weight! Weight around the middle is a sign of visceral fat, I believe - i.e. fat around your internal organs - and it's the most dangerous kind of fat in terms of our health, so it would be a good idea to try and shift that.
That said, 8.5 stone at 5 ft 9 in isn't overweight! Are you sure it's not your posture and/or tone/definition? Exercise might be better for you.
In general, it's better to live a low carb life, because high carb diet not only risks weight gain, but it's also bad for you - diabetes, high blood pressure, cancer, Alzheimers ...
That said, once you're at the weight you're happy with, the occasional slice of cake, piece of chocolate, glass of wine won't hurt - as long as it's not an excuse to suddenly devour all the carbs you can see!
You don't have to do strict Bootcamp to lose weight - you don't need to be in ketosis to lose weight; cutting down on carbs should result in weight loss. However, everyone is different in terms of the amount of carbs that they can tolerate, so you'll probably have to experiment to find out what works best for you.