An awful lot of people listen to HMQ's speech, WEBF - still part of the Christmas tradition and all that.
The question there is how many are a) sober enough to understand it b) remember the theme of it.
In general, survey after survey suggests that the public are very supportive of the armed forces, feel a great deal of pride in the services and regard the members of said body far more highly than they regard most other professions (especially those with the letters 'MP' after their name).
I'd respectfully suggest that the question is actually not one of how to go about getting support for the forces from the public, but how one goes about translating that general good will into moving defence to being one of the top priorities of the government through public pressure.
Problem is that with the NHS, Transport and education in such a mess, an immigration policy that makes the NHS, Transport and Education policies look effective, law and order policies that all-too-often place touchy-feely policing and protecting the rights of the criminal ahead of solving crimes and implementing effective punishment, etc, etc causing the public far more concern than the state of the forces (who always do what's asked of them, unlike many other departments of state) how do we get to that stage?
You've posed the question several times now - what's your answer? Not a dig - genuine enquiry to take the debate on.
[NB Restarting the Cold War and persuading the Russians to retarget all their ICBMs onto this country does not win any Christmas prizes]