Hi weight_loss and welcome!
I'm new-ish here myself but I've spent a lot of time reading these forums and looking at peoples' stats. My pharmacist told me that the Cambridge Diet and Lipotrim (which I am on) are very similar. With that in mind it seems that a common and achievable target is a stone a month.
Backing that up, if you look through members' stats in their posts, this seems to be quite accurate. The trend seems to be lose a lot in the first week (as this is mostly fluid loss), roughly between 6 and 10 lbs or more, and then each week slightly less but still between 3 and 6lbs.
Of course both figures can vary and I have read of members only losing a pound or as much as 7 or 8 pounds, but these tend to be exceptions.
Even if you figure on 3lbs a week, that is still pretty close to a stone a month.
Have a look through other members' stats for a better idea. Like I said, I am fairly new and am happy to be corrected.
Good luck with your adventure!
-Pete.