Many people find that military records are valuable in helping them trace family details.
Army service record: if you are fortunate enough to be able to find the soldier’s service record it is likely to include a good deal of personal and family information: next of kin, date of birth, date and place of marriage, addresses and pre-army occupations are all regularly found in these records.
Pension record: usually appearing as part of a service record (but in some cases a few documents did survive while the main service record was destroyed) a pension record often gives next of kin, age, address and medical details.
Campaign medals record: these generally do not include non-military details. Addresses appear in a very small minority of cases.
Silver War Badge records: these often include the man’s age but little more by way of personal or family information.
Records of death and commemoration: variable in terms of personal and family information, but it is usually possible to determine a place of birth, place of residence and/or place of enlistment. If provided by the next of kin it is also possible to find age, address and next of kin details.
Caveat
In the majority of cases of soldiers who did not lose their lives in the war, destruction of so many of the the service records in 1940 means that a soldier’s personal and family information is unlikely to be found through the military documents. Start out in hope, but with a realistic expectation that you may not find what you seek.