Hi Yoko

Welcome to the area. My kids are a little past the toddler stage so hopefully others will be along with more suggestions soon, but in the meantime you could try Edukids in St Sulpice (village about 6km towards Lausanne from Morges).

http://www.edukids.ch/Home.php

They run a range of playgroups, music, coffee get-togethers, etc, attended by both English and French-speaking mums (their pre-school is bilingual).

kodokan