I think Ibbi is right - in fact, in CCF (not sure about ATC) there is a rule that if attending annual camp before completing CCF IOT you could not attend in uniform (though would be paid). Check with HQAC as your commission will in fact be backdated to the date of your board.
messkitonline did mine and are excellent (quality superb) except (a) evidently they smoke, which means the uniform comes pre-impregnated, and (b) they had no idea where to put the VR(T) badges - better to order them separately and put them on yourself, in my experience...
Messkitonline is made to measure, and therefore £600 against Snaith off the peg £500.
And sadly, no, you can't get it at the 'issue' price...
Tim