No doubt about it, that's his service record, or at least his record for his first period of enlistment, and his place of birth was definitely Small Heath in Birmingham.
There is only one birth registration which matches that information in regards to place and time.
He was born in September but his birth was registered as Fred Whitehead in the October, November, December quarter of 1893 which is fine, because parents have 6 weeks in which to register a birth,...his birth was registered in the Aston Registration District of Birmingham in County Warwickshire as it was then, and at that time Small Heath was in the Aston Registration District.
The birth registration index ledger reference is Volume 6D Page 232.
You can get a copy of his birth certificate for about £10 from either the UK General Register Office
http://www.gro.gov.uk/gro/content/ or from Birmingham Register Office, which now holds the Aston Registers for that period.
http://www.birmingham.gov.uk/cs/Satellite/certificate?packed...He enlisted in late 1914, so he volunteered, conscription wasn't introduced until 1916, but he didn't enlist for the duration of the war, he enlisted for a normal term of enlistment of 12 years, after which he had the option to either leave, or to reenlist and serve for a further term of 9 years to complete 21 years service which would give him a maximum pension entitlement.
That seems to have been what he did, and the rest of his service record for his second period of enlistment should be with the MOD.
It's common for RN service records not to mention spouses or children, although doubtless that information was listed on separate documents which either haven't survived, or which haven't been made available, the RN certainly would have recorded that information, for the obvious reasons, and also because he would have a portion of his wages paid regularly to his wife.
His WW1 campaign medals were issued to him while he was serving in HMS Dolphin the RN shore base submarine school.
http://en.wikipedia.org/wiki/HMS_Dolphin_(shore_establishmen...)
He was awarded the 1914-1915 Star.
http://en.wikipedia.org/wiki/1914%E2%80%9315_StarThe British War Medal.
http://en.wikipedia.org/wiki/British_War_MedalThe Allied Victory Medal.
http://en.wikipedia.org/wiki/Victory_Medal_(United_Kingdom)