period of temporary absencemeans— a a period of absence not exceeding 13 weeks, beginning with the first whole day on which a person resides in residential accommodation where and for so long as— i the person resides in that accommodation, ii the part of the dwelling in which he usually resided is not let or sub-let, and iii that period of absence does not form part of a longer period of absence from the dwelling of more than 52 weeks, where he has entered the accommodation for the purpose of ascertaining whether it suits his needs and with the intention of returning to the dwelling if it proves not to suit his needs;