Would privately renting for a year to trial it be an option?
Found a few bits for you:
From JSP 464. Chapter 3 is the bit you need.
Entitlement criteria. To be entitled to SFA Service personnel must be:
a.
Aged 18 or over, have completed initial training and be serving on a regular engagement with the UK Armed Forces, or be a Full Commitment (FC) Reservist as defined in single Service instructions. For those personnel under 18 years of age the parent unit must accept responsibility for their behaviour until the 18th birthday.
b.
In Personal status category (PStatCat) 1 (See footnote1), 1C, 1S or 2 as defined in Appendix 1 to Annex D to Chapter 1.
c.
Have at least 6 months to serve at the station where they qualify for SFA.
You can see the definitions of PStatCat here
Basically the main bit is:
(1) A legally married member of the Armed Forces, who lives with their spouse, or who would do so but for the exigencies of the Armed Forces.
(2) A member of the Armed Forces, who is registered in a civil partnership in accordance with the Civil Partnership Act 2004, or is in a civil partnership under an overseas scheme recognised under that Act, and who lives with their registered civil partner, or who would do so but for the exigencies of the Armed Forces.
Your OH could get SFA for him and the children if he had custody of them, but you couldn't live there with him.