Stereo head unit swap, for DAB/APPLE PLAY unit...help!

Hey all.

My other half wants a stereo upgrade for Christmas. 

Car is a mk2 Auris hybrid 1.8, 2012

She wants a unit with DAB that runs off bluetooth from an iPhone.

How do I get the replacement unit to fir exactly ?

Is this a big job?

Cheers 

sorry I can't upload pics