Thanks for the replies.
Vicx - did you find the hypnotherapy helped? I have thought about trying it, as I don't like to take medication if there is an alternative route, and this seems like a good one. Is it expensive? Something you can get on NHS?
Thank you both for the advice. I normally do breathing techniques when I feel a panic attack coming on, but this one hit almost instantly that I was already hyperventilating as soon as I knew what was happening, it's hard to do breathing techniques at that point.
Not a great thing to happen during my first week on WW, but I have still stuck to it