Complex sentence: Momentum has over 150 local groups across the UK, and since launching its membership scheme in April 2016, and in October 2016 claimed to have over 20,000 full members, as well as over 200,000 supporters.
Split into simpler sentences: Momentum has over 150 local groups across the UK. In October 2016, Momentum claimed to have over 20,000 full members, as well as over 200,000 supporters.