Was King Henry VIII, mid-late in his reformation campaign, motivated more by theology or absolutist drive?

Short Answer

The second one.

Long Answer

Many historians believe that at the very beginning King Henry VIII was driven more by personal reasons than theological reasons. Quite a lot of good sources are cited in this wikipedia article and this one.

It all started with Henry's troubles with Queen Catherine --his first wife. Henry was obsessed with a male heir to his throne and Catherine had only provided him with one child (who survived infancy) --Mary (later to become Queen Mary I of England). Henry wanted to annul his marriage to Catherine so that he could marry Anne Boleyn but Catherine (daughter of Queen Isabella I of Castile and aunt to the Holy Roman Emperor Charles V) had the support of Pope Clement VII, who would have obviously feared Charles's armed forces. Indeed, when the matter was first raised the Pope had been imprisoned by Charles. The Pope delayed the issue and insisted that it be settled in Rome and not England. Henry made several attempts to persuade the Pope to side with him and grant him the annulment but the Pope never did so. And thus Henry started challenging the Pope's authority over religious matters.

I quote Wikipedia now:

Breaking the power of Rome in England proceeded slowly. In 1532, a lawyer who was a supporter of Anne [Boleyn], Thomas Cromwell, brought before Parliament a number of acts including the Supplication against the Ordinaries and the Submission of the Clergy, which recognised Royal Supremacy over the church.

The result were the Royal Acts of Supremacy and consequently Henry was free to do as he saw fit (even on religious matters). He annulled his marriage to Catherine and married Anne Boleyn (1533).

The religious reformation continued. The King still remained Catholic but questioned many Catholic practices. Many Lutheran and Catholic practices were condemned and adherents of both streams were persecuted systematically (see this for sources) --causing great confusion and debate over the nature of the new English religious order.

Although it all started with Henry's Great Matter, which can be characterized as a political issue, the debate soon got entangled in many theological issues as Henry's interests clashed with those of the papacy. The chief problems came from two main questions:

Who holds the supreme religious authority?

Before the English Reformation began, bishops held considerable authority and power and were more or less independent of the King (on religious matters). They themselves were governed under Roman Cannon Law (Papal law, not the law left by the Roman Empire, although Papal law itself came from several Byzantine decrees). Even their appointment was done by the Pope and not by the King. As such, Bishops could and did subdue the King's authority on religious and spiritual matters in their jurisdictions.

To counter this, especially to remove challenges to his marriage question, Henry had his ministers pass The Ecclesiastical Appeals Act (1532) that forbade appeals to the Pope on religious matters and made the King chief authority on such appeals. To limit their authority further, an act was passed in 1535 to destroy the "corrupt" monasteries (see below).

Who should receive the taxes from religious institutions?

Abbeys and Monasteries in medieval England were fairly rich. These institutions paid a large portion of their taxes to Rome. And that was in turn because they were governed by Rome and not by England. Although Henry started off with a very prosperous economy, his extravagant spending on navy, infantry, and construction left the exchequer in debt. Monasteries and Abbeys were a lucrative source of revenue for this poor King and his administration.

The Act in Conditional Restraint of Annates limited the amount of taxes such institutions could pay to the Pope. Two years later, they were completely forbidden. This wikipedia link claims (with sources):

The Dissolution of the Monasteries provided a means to replenish the treasury and as a result the Crown took possession of monastic lands worth £120,000 (£36 million [in today's terms]) a year.

The six articles were adopted by Henry much later (1539) and although the English acts passed hence bear an outward facade of other theological differences, it all started with Henry's Great Matter and therefore it can be said the English Reformation under Henry VIII was mainly motivated by an absolutist drive (even in the mid-late duration of his campaign). The protestant nature of the reformation actually took much shape under Elizabeth I's rule.