The scan reference you gave is just the name of the image as it exists within the FreeBMD database. It doesn't give you the GRO reference.
To get a certificate from the GRO you need the year and quarter information, the registration district and the Vol and Page number. So taking the example below, the reference for the birth certificate for John Smith would be John Smith 1900 Qtr1 (or Jan-Mar) St Geo East Vol 1c page 347.