Partly answered my own question
at this website:
http://www.lcacc.org/index.html
From the site:
Aircraft currently approved for scheduled services
Here are brief details of the principal types of aircraft currently approved for use at the the Airport to provide scheduled services. (Note: The Maximum Take off and Landing Weights of aircraft are not always available at London City Airport).
ATR 42
BAe 146/Avro RJ family
BAe 4100 Jetstream
DHC-6 Twin Otter
DHC Dash 7
Bombardier Q Series/DHC Dash 8
Dornier Fairchild 228 Embraer 135
Dornier Fairchild Do328
Fokker 50
Fokker 70
Saab 340
Saab 2000
Shorts 360-300
So, no Fokker 100 and no E170, or any Bombardier RJs for that matter.
And for info, the A318 is quoted at 107 pax, RJ100 at 100-112.