You don't say how much time you have available to you. Why don't you do both? Spend a week in each place. Don't worry about language in Paris, you can get by if you don't know a single word of French, but I think you would enjoy learning a few words like, bonjour, Merci, au revoir, etc.
Check the price of the air tickets to Paris and London and take the one that is the least expensive. Then take the tunnel between Paris and London. Both cities can be done on a budget.