Your research council's website should have information to tell you whether they will approve this or not, and failing that contact details for you to contact them to ask your precise question. My funding council has detailed downloadable guidelines for current award holders, covering everything, including this. They (AHRC) would only generally sanction breaks for extreme medical reasons. Taking a break isn't a problem for the university authorities, and if the funding council approves it your funding will be put on hold for the relevant number of months, as will your PhD.