When Henry VIII started the CofE they were essentially Catholics that didn’t recognize the Pope, right? So when did they abandon clerical celibacy? When did they switch from Latin to English?
He didn’t. He took the existing national church structure and declared it independent of Papal intervention.
Some priests and bishops, including Cranmer, married secretly under Henry. Most of the freeing from clerical celibacy came about under Edward VI shortly after Henry’s death.
First Book of Common Prayer.
King Henry never accepted marriage of the clergy as summarised by this web-site on the
Thirty Nine Articles, a summary of the Anglican doctrine:
When the Pope excommunicated Henry in 1538, the King reacted in proclaiming his orthodoxy by applying ‘The Whip with the Six Strings’ (The Six Articles of 1539), which was incorporated in an Act of Parliament popularly called ‘The Bloody Statute of the Six Articles’.
The Act compelled the acceptance of Transubstantiation (though the actual word is avoided), Clerical Celibacy, Communion in One Kind, the obligation of Vows of Chastity, the use of Private Masses, and Auricular Confession. Thenceforth no further move towards the reformation of the doctrine of the Church was possible while Henry VIII lived.
Things changed under Elizabeth. In 1571, Parliament passed the Thirty-Nine Articles in essentially their final form.
Article XXXII dealt with the marriage of the clergy:
OF THE MARRIAGE OF PRIESTS**
Bishops, Priests, and Deacons are not commanded by God’s Law, either to vow the estate of single life, or to abstain from marriage: therefore it is lawful also for them, as for all other Christian men, to marry at their own discretion, as they shall judge the same to serve better to godliness.
So, from 1571 onwards, there’s not been any requirement for celibacy in the Anglican church.
Oh, and a minor point from the OP:
The Anglican position is that Henry didn’t start the Church of England. He broke off from Rome, but the Church of England was started by S. Augustine’s mission. There has been continuity throughout that time.
Edward and his advisors published a new set of articles in 1553, the
Forty-Two Articles, but it doesn’t look as if they were ever official:
In 1551, Cranmer was directed to prepare a Book of Articles, which he showed to some of the Bishops. But it was May 1552 before the Council asked Convocation for them. They originally numbered 45, but after revision by the Royal Chaplain, were reduced to 42, and published, by Royal command, in Latin and English, in 1553 as The Forty‑Two Articles. They were mainly the work of Cranmer, who in compiling them made use of the Thirteen Articles of 1538, and the Confession of Augsburg.
Mary came to the throne, the Church went back to Catholic doctrine:
It is still doubtful whether they were approved by Convocation, but the point is not of great significance, for they were put forth by the King’s authority only seven weeks before his death. On the accession of queen Mary they were dropped – they had not been enforced by Act of Parliament and there was no need to repeal them. Once more the reforming process was halted.
So, I would submit that the definitive change was under Elizabeth.