Hey Tim, and welcome to the forum, Lausanne and UNIL! I'm a postdoc at UNIL in ecology & evolution, so I guess you will be in the same building (Biophore) as me! We must meet up when you're over here.
I know exactly what you mean about the difficulties in arranging accommodation from England. I've taken my apartment over from a PhD student who is leaving. Maybe you could try to contact your group secretary and see if they could send an email around the department to ask if anyone is leaving their apartment soon.
I have also had a good experience with renting a temporary apartment for 2 months from Arc Lémanique Immobilier (
http://www.arc-lemanique-immobilier....ion_courte.php). They offer fully furnished studios on a monthly contract. They also have some long term furnished studios (which is useful as nearly all apartments over here are unfurnished -- I'm grappling with Ikea delivery at the moment for my new place!).
Hope that helps a bit!