From BBFC ratings:
"A young man masturbates to pornography, which is shown on screen in explicit detail. There are strong verbal sex references, some of which are crude."
THE PERFECT DAVID is an Argentinian drama in which a young bodybuilder obsessively trains to become his artist mother's muse.
www.bbfc.co.uk
I don't think there is much to expect, at least in terms of unsimulated sex. The explicit act will probably be either him explicitly masturbating or a porn movie being explicitly displayed.