Dear Kavya,
When you release a service entry sheet with the green flag, and save, it will automatically post a goods receipt in the background. I think it's only using some extra authorization object, but not directly calling MIGO. There is a buyer role in standard SAP, which can be checked for your purpose: SAP_SR_BUYER_5.
I don't know what kind of services you are getting, but it's also possible to set up for PO documents, that you will not need GR(SES), but only invoice receipt to be posted.
Tamas