XC60 AWD New tyres
 

I have a 2013 xc60 2.4 D5 AWD. It currently has Hankook Dynapro HP2 all round. The fronts are pretty worn but there is lots of tread left in the rears. I wanted to get Michelin crossclimate's fitted but only on the front for now as there is still so much tread left on the rears. Will this be ok or will it cause problems?

It will be absolutely fine.
If worried about a difference in grip over winter, ie dont want to unwittingly lose the back-end, put the CC on the back and the Hankook on the front. The CC dont give masses of extra grip in inclement weather, the difference will be that of two different summer tyres (which is really what they are) than 2 summer 2 winter, its just that the CC can do snow too and is a -little- better on ice.

As said in the other section - mixing tyres of slightly different sizes and condition will not cause any harm to the AWD system despite what some manufacturers and fitting chains may tell you....

Otherwise why would Volvo offer space saver spare wheels??

Rear tyres move to the front and put the new on the rear.