Hi Sheila-Ann

Have a read of the links below information about what FreeBMD is and does - which essentially, transcribes the original BMD Indexes, and therefore provides you with names, Registration Districts and GRO ref numbers to be able to order the certificate.
FreeBMD in itself, doesn't provide (doesn't have) whatever information may be contained in any certificate they have indexed. When you do order a certificate, you can make certain provisos, such as the name of parent(s) if you know it, to avoid ending up with incorrect certificates. Having said that, the Index found for Gertrude is unlikely to be any other than your Gertrude!
http://www.freebmd.org.uk/http://www.freebmd.org.uk/FAQ.htmlhttp://www.freebmd.org.uk/Certificates.htmlHere, you will also find information about what you can expect (hope) to find on an actual Certificate.
The birth certificate of Gertrude will not tell you anything of the parentage of Henry and Eliza. It will (should) tell you the names of the baby Gertrude Annie's parents (mother at least!), mother's maiden name, father's occupation, and the address of the birth, plus the name and address of whoever informed of the birth.
With the 1881 Census information, you can now look for the family backwards and forwards from that time in the Census - this may give you further clues (for eg: relatives living with them, the ability to compare stated pob and ages for consistency etc)
You are fortunate Gertrude died in Scotland, therefore her death certificate naming both parents and her mother's maiden name.
Looking at the 1881 Census, we can see the eldest child there is stated b abt 1867.
FreeBMD Marriage entry, is probably the correct index for her parents marriage:
Henry COPELAND and Eliza PROCTOR on the same page containing 2 grooms and 2 brides
(when ordering, the proviso is that COPELAND marrried PROCTOR)
Sep Qtr 1865 Sleaford - Ref: Vol 7a, pg 661 661
The marriage certificate, should hopefully tell you the names of the father's of bride and groom. And witness' to the marriage may be other family members who can be connected via Census.
Cheers
AMBLY