west as in Clementi?
or west as in Bukit Batok? Boon Lay?
Clementi - Church of the Holy Cross around where the NUS High
School is
Bukit Batok - St Mary's of the Angels
Boon Lay - St Ignatius
but best is clicky here => Singapore
Catholic Church Directory
when you go to the church, just ask to speak to anyone who is
helping out there... if you really want to know the faith more,
just ask to join the RCIA or Rites of Christian Initiation of
Adults..
may God bless you 
Boon Lay - St Ignatius?!
St Ignatius is at Bukit Timah, Boon Lay is St Francis of
Assisi. (:
