If you sign up to a FTRS contract you need to be careful if you are thinking of taking your family with you. Only on Full Committment are you entitled to service accommodation - and FC is now normally only granted for those going on Operations.
It is possible to get service accommodation on FTRS Limited Committment if there is surplus in your units location and your CO puts up a strong case, but there may not be enough to go around anyway.
If you do get FTRS FC and consider moving your family with you, consider renting out your property, if you own one, rather than selling it. If you are in rented/council accommodation you have a big decision to make as when you return to your local area you may not be looked on favourably for a council property as you will have voluntarily given one up before.
All this advice can be gained from reading the Terms & Conditions of Service or the DCI published in 2004 which explained FTRS.
Have you not considered joining the Regs straight out instead of FTRS?