The Cambridgeshire County Council births, marriages and deaths index (CAMDEX -
http://www.cambridgeshire.gov.uk/community/bmd/certificate/Camdex/) includes a code in marriage references indicating at which church or registry office/nonconformist district the ceremony took place. I have pieced together the following partial list decoding those references and post it here in case it is of any help. If you know of any other code/church matches, please add them below and I will update the list.
The parishes within the current Cambridge Registration District are arranged predominantly alphabetically (with a few anomalies in the Cs), so it may be possible to guess at the location of missing codes.
EDIT: Grateful thanks to Paula, Dave and Julia on the Eng-Cambridgeshire rootsweb list who have provided many of the missing parishes and suggested some places needing codes (which are listed separately).
Cambridge Registration District CE001 Abington Piggotts
CE002 Arrington
CE003 Ashley cum Silverley
CE004 Babraham
CE005 Balsham
CE006
CE007 Barrington
CE008 Bartlow
CE009 Barton
CE010 Bassingbourn
CE011 Bottisham
CE012 Bourn
CE013 Boxworth
CE014 Brinkley
CE015 Burrough Green
CE016 Burwell
CE017 Caldecote
CE018 Cambridge All Saints
CE019 Cambridge St Giles
CE020 Cambridge St Luke
CE021 Cambridge Holy Sepulchre
CE022 Cambridge Holy Trinity
CE023 Cambridge St Andrew the Great
CE024
CE025 Cambridge St Andrew the Less
CE026 Cambridge St Barnabas
CE027 Cambridge St Benedict
CE028
CE029 Cambridge St Clement
CE030 Cambridge St Edward
CE031
CE032 Cambridge St John the Evangelist
CE033 Cambridge St Mark
CE034
CE035
CE036 Cambridge St Mary the Great
CE037 Cambridge St Michael
CE038 Cambridge St Mary the Less
CE039 Cambridge St Matthew
CE040 Cambridge St Paul
CE041
CE042 Cambridge St Philip
CE043
CE044 Cherry Hinton
CE045 Chesterton St Andrew
CE046 Chesterton St George
CE047
CE048
CE049 Trumpington
CE050 Carlton cum Willingham
CE051 Castle Camps
CE052 Caxton
CE053
CE054 Comberton
CE055 Conington
CE056 Coton
CE057 Cottenham
CE058
CE059 Croydon cum Clopton
CE060 Dry Drayton
CE061 Dullingham
CE062 Duxford St John
CE063 Duxford St Peter
CE064
CE065 Elsworth
CE066 Eltisley
CE067 Fen Ditton
CE068 Fen Drayton
CE069 Fowlmere
CE070 Foxton
CE071 Fulbourn All Saints
CE072 Fulbourn St Vigor
CE073 Gamlingay
CE074 Girton
CE075 Grantchester
CE076 Graveley
CE077 Great Abington
CE078 Great Chishill
CE079 Great Eversden
CE080 Great Shelford
CE081 Great Wilbraham
CE082 Guilden Morden
CE083 Hardwick
CE084
CE085 Harston
CE086 Haslingfield
CE087 Hatley St George
CE088 Hauxton
CE089 Heydon
CE090 Hildersham
CE091 Hinxton
CE092 Histon
CE093 Horningsea
CE094 Horseheath
CE095 Ickleton
CE096 Impington
CE097 Kingston
CE098 Kirtling
CE099 Knapwell
CE100 Landbeach
CE101 Linton
CE102 Litlington
CE103 Little Abington
CE104
CE105 Little Eversden
CE106 Little Gransden
CE107 Little Shelford
CE108 Little Wilbraham
CE109
CE110 Lode
CE111 Lolworth
CE112 Long Stanton All Saints
CE113 Long Stanton St Michael
CE114 Longstowe
CE115 Madingley
CE116 Melbourn
CE117 Meldreth
CE118 Newton and Milton
CE119
CE120
CE121 Orwell
CE122 Over
CE123 Pampisford
CE124 Papworth Everard
CE125 Papworth St Agnes
CE126 Rampton
CE127 Sawston
CE128 Shepreth
CE129 Shudy Camps
CE130 Stapleford
CE131 Steeple Morden
CE132
CE133 Stow cum Quy
CE134 Swaffham Bulbeck
CE135 Swaffham Prior St Mary
CE136
CE137
CE138 Swavesey
CE139 Tadlow
CE140 Teversham
CE141 Thriplow
CE142 Toft
CE143 Waterbeach
CE144 Wendy cum Shingay
CE145 Westley Waterless
CE146 Weston Colville
CE147 West Wickham
CE148 West Wratting
CE149 Whaddon
CE150 Whittlesford
CE151 Willingham (by St Ives)
CE152 Wimpole
CE153 Wood Ditton
Parishes missing codes in Cambridge Registration District Cambridge St Botolph
Cambridge St Martin
Cambridge St Peter
Cambridge St Stephen
East Hatley
Harlton
Little Chishill
Oakington
Stetchworth
Ely Registration District CATH Ely Cathedral
CHAM Chettisham
CHPM Chippenham
COEY Coveney
ELMA Ely St Mary
FOAM Fordham
HAAM Haddenham
ISAM Isleham
KETT Kennett
LIDM Little Downham
LIOE Little Ouse
LIGE Littleport St George
LIMA Littleport St Matthew
LITD Little Thetford
MEAL Mepal
PROW Prickwillow
SNLL Snailwell
SOHM Soham
STAM Stretham
STEY Stuntney
SUON Sutton
TRIN Ely Holy Trinity
WENT Wentworth
WICK Wicken
WILB Wilburton
WITM Witcham
WITD Witchford
Fenland Registration District CWnn Wisbech areaCW01 Gorefield
CW02 Guyhirn
CW03 Leverington
CW04 Murrow Corpus Christi
CW05 Newton
CW06 Southea Emmanuel
CW07 Tydd St Giles
CW08 Wisbech St Mary
CW09 Wisbech St Augustine
CW10 Wisbech St Peter
CW11
CW12 Elm
CW13 Friday Bridge
CW14
CW15 Parson Drove
Parishes missing codes in Wisbech area Christchurch
Coldham
CMnn March areaCM01 March St Wendreda
CM02 March St John
CM03 March St Mary
CM04 March St Peter
CM05
CM06 Doddington
CM07 Manea
CM08 Wimblington
CM09 Coates
CM10 Whittlesey St Andrew
Parishes missing codes in March area Benwick
Chatteris
Whittlesey St Mary
Register offices / nonconformist districts CAM Cambridge
LINT Linton
R-ELY Ely
ROM March (from 1938)
RONW North Witchford (1837-1938)
ROW Wisbech
ROWH Whittlesey