I was actually taking the Eurostar from London to Paris myself on the 8th and my train was cancelled. Eurostar isn't accepting any bookings from the 5th to the 8th. I looked at flying on the 8th and BA / Air France wanted 550$ one way. Easyjet wanted 200$ and like you I was concerned about easy jet cancelling. I ended up cancelling my hotel in Paris and decided to remain in London for the duration of my trip. If you do go to Paris be sure and allow extra time to get to the airport as there will be few trains and probably a great deal of traffic. I hope it works out for you!