What does Philip Larkin try to convey in his poem "A study of Reading Habits"?

I just have a few things to add to the very comprehensive
answer provided above. I would point out that in a number of Larkin's poems, there is a
definite and deliberate discrepancy between the title and the ending of the poem. Larkin
seems to delight in shocking his readers through the use of formal English in titles,
such as his famous "This be the verse" and then the use of trivial and colloquial
English therein. We can see this in this poem with the rather formal and pompous title
of "A Study of Reading Habits" and the colloquial language that he uses to end the poem,
where he argues that "Books are a load of crap." However, we need to be aware that
Larkin is far more subtle than his poetry at first glance would suggest. Just as he is
not really arguing that we should "get out" of life "while we can" and not have any
children (his argument in "This Be the Verse"), he is not really arguing that "Books are
a load of crap" in this poem.

Rather, what he is saying is
that it is how we use books and literature can be unhealthy and dangerous depending on
what we do with them. Clearly the examples that the speaker gives are rather unhealthy
ones. The fantasy worlds in literature allow the less-than-physically impressive speaker
to maintain some level of self-esteem through believing that he is able to show physical
supremacy against "dirty dogs twice my size." Likewise, he is able to fulfill and
gratify his sexual fantasies and cravings through literature, suggesting a rather
disturbing and grotesque series of fantasies and sexual
violence:

The
women I clubbed with sex!

I broke them up like
meringues.

The last stanza
suggests that the speaker does not read because these fantasies have become "too
familiar," which leads to the conclusion of the poem, which is vintage Larkin in its
cynical and sarcastic viewpoint. For an academic such as Larkin, he is not seriously
arguing that books are nothing more than "crap." He is pointing towards the excesses of
imagination and fantasy to which they can be used. This is the "study of reading habits"
that is explored through the poem.