پاسخ دهید - English

It's "Were he to have more free time," not 'Were he have to." "Have to" in English means "must," like "I must go to the store" = "I have to go to the store."

How often we use it is a demographic issue: It depends on the age and/or region of the speaker. You probably would never hear this inversion said by a young American speaker, but you would probably hear it all the time in England - especially among older populations. Either way, it's a great skill to be able to use it!

I always hear and see it as a 3rd-person singular (Were he/she). For "I," "you," "we," and "they," I always see "If I were to go.../If you were to go.../If we were to go.../If they were to go..." etc. Eg: "Were he to go the store," vs. "If were to go to the store..."

ExRanger, or another Brit, might have more information on these forms as well.

It's quite formal and you'll see it a lot more in writing than you'll hear it in conversation.

Only two things to add:

1. One could "invert" accordingly: "Were he to have more free time, he would travel more."

2. HyaSky: I am American-born, not "British" nationality, although my mother and her parents were born in England; however I will allow that while i was reared @ New York (Westchester County) and schooled @ Chicago (University of Chicago Lab Schools), my brother and I endured the influence of "British usage" owing to the presence of our mother and her parents, w/ whom we spent most summers in New England. That said, the community in which we were raised, Hyde Park (Chicago), is a South Side community where we we immersed in not only a panopoly of English "dialects", but were as well "surrounded", as it were, by Black English speakers and the unique characteristics of so-called "ebonics" (note: a term w/ which I do not find favor but seems to have found favor among contemporary linguists interested in "urban dialect")
Also note that in Chicago our nearest relatives, i.e., our father's family, were NOT of British origin, rather came to The States from (mainly) Hungary and Tatarstan (in USSR) during the "First Great Migratory Wave" to the USA, circa 1900. These people spoke English as a second language and thus carried to their graves English imbued with phonological, lexical, and structural elements reflecting Hungarian, Yiddish, and Turkic.