Apple has refreshed its iPad Air range and introduced a supersized new 13-inch model. For the first time, those who want the biggest display on an iPad won’t need to spend over £1,299 for the top-of-the-line iPad Pro, which previously had the monopoly on this mammoth screen size. Instead, the new iPad Air is available in the same 11-inch and 13-inch display sizes. Prices start from £599 for the 11-inch iPad Air with Wi-Fi, rising to £749 for the Wi-Fi + Cellular model. The 13-inch iPad Air starts at £799 for the Wi-Fi-only tablet, increasing to £949 for a model with both Wi-Fi and Cellular dat…