So I'm chickening out, basically. And I'm thinking, anyway I'm gonna take the adrenal tonic for months, wouldn't it take care automatically of the gluten intolerance - supposed I have it? without passing by staying gluten-free?
Yes, if the gluten problem is an allergy. Building up your adrenals will also reduce the inflammation.
Can I take, say, a month or two of adrenal tonic and after that check if I'm gluten intolerant? or would the tonic not work properly if there's some food in the system that my body is intolerant to?
That is fine. If it is allergies most people have reported a reduction in symptoms within 3 days and pretty well controlled within a few weeks. So if it is an allergy you should be good to go after a month or so as long as you remember to watch the stimulants like caffeine and stress.