I used to go to 'Pregnastics' at my hospital. It was basically aerobics, pliates, stretching etc for pg women.
The physio's that took our class always made us take our heatrate, and they said it is good to aim for between 120bpm and 140bpm, but NOT over 140.

I would suggest talking to your Dr about it Bertie... as sometimes they do not recommend very high impact excercises during any stages of pg.
Is it possible to take it a bit slower at bootcamp?

I agree with Fi, I think it depends how overweight you are as to whether it will affect TTC. I have heard of some ppl only falling pg after they have lost weight, but they were quite overweight to begin with.
And I myself only fell pg after I had gained a few kilos as I was underweight before pg.