Evans do sell Cube
Maybe not all stores though. Only found out last week when I bought my new Trek that not all Evans stores stock all brands. Apparently each store is 'licenced for certain brands and my local store (Kendal) can't stock them as Wheelbase in Staveley and few miles away are authorised Trek resellers.
However, you can purchase from the Evans website and have them delivered to your local store who will build them up.