What Editor Bob said.
Hannover4EnglishSpeakers has its monthly meetings (next one is this Wednesday), plus occasional afternoon tea-times and pub quiz nights, and twice-monthly meetings for families with small kids. We announce them on TT sometimes, or otherwise you can
check our calendar.
Other English-language groups in Hannover:
Anglicans in Hannover
Monthly church services in English
Anglophiles
Meets twice monthly, currently at the KDW in Osterstraße
German-Australian Society
Hannover-Bristol Society
Regular meetings in German, but with occasional English conversation evenings and get-togethers
International Women's Association of Hannover
SpeakEasy
Meets on last Monday of each month at the Bayrische Botschaft on Thielenplatz; also have occasional hikes and other meetings
There is also an informal group calling itself GNO for "Girls' Night Out" that the wimmin-folk can find on Facebook. I have heard that the university also has a conversation group, but don't know much about it.
If you do set up another group, please let me know and I'd be happy to swap links. But Hannover's not quite so dead as you think. Just that the Hannoverians don't seem to post much on TT, and it's not for lack of us Hannover TTers trying to change that.
Cheers,
Fairfax71