Assuming you're in or near the city you'll be in one of the following constituencies:
|South East Cambridgeshire||James Paiceemail@example.com||http://www.jamespaicemp.com|
|South Cambridgeshire||Andrew Lansleyfirstname.lastname@example.org||http://www.andrewlansley.co.uk|
The City constituency is quite small and is surrounded by the other two constituencies and these include some parts of the city, so you can be in the City Council district but not in the City constituency. For example Girton, Granchester and Trumpington and everything south of a line along Lensfield Road, Hills Road and Cherry Hinton Road, Lime Kiln Road and Worts Causeway is South Cambridgshire.
Histon, Impington, Milton, Fen Ditton, Quy, Teversham Fulbourn are all in South East Cambridgeshire. The older part of Cherry Hinton is Cambridge, the new part, South East Cambridgeshire. There is a web site you can consult which will tell you your constituency based on your postal address. WriteToThem provides another means of contacting based on postcode.