Hi Ceri
i did this tour in November 2014, i loved Peru, you'll find that Lima can be quite damp and murky but things warm up after the first few days then it can get cold again at the end in Cusco so take warm cardigans for the evening and early mornings for getting off the coach and a light rain jacket comes in handy also, altitude can be a problem but just take it easy and drink the cocoa tea which is available everywhere and plenty of water
my favourite place was Arequiba
anything you wish to know just ask
enjoy it
Dave