Originally Posted by Raffles

As long as you understand that BA's punctuality out of LHR is SUBSTANTIALLY worse than FR's from Stansted ....

If you are concerned about getting there on time, you've taken the wrong route. The only benefit of BA is that it has numerous Milan flights every day in case one goes wrong or is delayed, but that is only of help to you if your schedule has enough flexibility in it. There is certainly no guarantee that BA would get you on the next flight if yours went wrong unless you had a Club ticket.

If your Ryanair flight was cancelled for any reason (VERY unlikely) there are loads of flights to Nice from Stansted and you could take the train from there.