If you are looking for a studio that is near Bastille and not super fancy, you might be interested in Maison Zen.

Another Ziner recommended it to me and we loved it - a few years ago, we stayed for 3 weeks. http://www.maisonzen.com/

It is a little unusual in that the studios are in a Zen house. You needn't have anything to do with that, but it is quiet and you must take off your shoes at the front door. There is a shoe rack there.

We loved it. Friendly people, reasonably priced and safe. The kitchen is only a kitchen corner but we found it quite adequate. Near great bakeries and a fabulous market and a laundramat. We walked everywhere! Great bistro on the corner and others nearby. Near the Promenade Plantee: http://www.promenade-plantee.org/ Near Gare du Lyon and Bastille.

We also took the Eurostar. We found that we were able to change our reservation at the last moment. BTW, we took the Eurostar to Ashford in Kent rather than going in to London. Just in case that suits your travel plans better.

Frances Toronto, Canada