Which of Sir Thomas Wyatt's poems speaks of escaping the corruption of King Henry?

I think you are probably referring to Thomas Wyatt's poem "Mine own John Poynz." In this poem, which takes an epistolary form, as a letter to a friend, Wyatt explains why he has chosen to go home and "flee the press of courts." He explains that he no longer wishes to "live thrall" beneath the eyes of "lordly" people. He does not, he says, "scorn" the power of the important men at court, but he does state that he has less "esteem" for them than he does for "common" people.
Wyatt goes on to say that he cannot "do so great a wrong / To worship them." His depiction of those at court is condemnatory: they are "as wolves"; they "make deceit a pleasure" and to stay in court is to "with innocent blood... feed myself fat." Wyatt's reference to Caesar, in this poem, as in others, seems to be an allusion to King Henry. Wyatt's poem continues to suggest that there is hypocrisy alive in court, where one lie is believed over an obvious truth, simply because it better fits the purposes of the court. While at court the "double face" tendency is to take the "nearest virtue" as a means of pretending away all the other recent vices, Wyatt says that he is unable to learn how to live like this. Rather, in order to maintain his honor and remain a Christian man, Wyatt is choosing to take himself away to "Kent and Christendom," the suggestion being that the corrupt court lies outside the bounds of Christendom.
Wyatt wrote many poems which are of historical interest because of the insight they offer onto the court of Henry VIII. Another of his, "Innocentia Veritas Viat Fides Circumdederunt me inimici mei," is thought to have been composed upon the execution of Anne Boleyn, with whom Wyatt was reportedly in love.