The oft quoted 5 hour tailwheel conversion course is probably a reasonable amount of time to get a grasp of the basics of tailwheel flying, not that I'm an expert and in any way qualified to judge
There are some good books you can read beforehand, such as Harvey S Plourde's "The Compleat Taildragger Pilot".
As for Tiger Moths, I had about 50 hours total time in tailwheel aircraft (J3 Cub and Chipmunk) when I first joined The Tiger Club and they bravely sent me solo for the first time in one of theirs after 1h 15m dual. On the
Tiger Club website it says they recommend having at least 20hrs tailwheel experience before flying their Tiger Moths. I can thoroughly recommend them for tailwheel training if you're anywhere near the Headcorn neck of the woods.
That first 15m solo in a Tiger Moth is still one of the high points in my limited flying career
WF.