Is there a taxi service from cairnryan to stranrar rail stn and how long does it take?
What's your final destination?
If you are going from Belfast to Glasgow or Edinburgh, go by direct coach. The 923 service is jointly operated by Ulsterbus and Scoittish Citylink; coaches run city centre to city centre and go over on the ferry so you don't even need to handle your luggage.
There are also services from Belfast to English cities.