The CRJ-700 could definetly operate within British Europeans fleet quite well, considering that they have until recently operated the CRJ-200. CRJ-700 is partly built un the UK by Shorts this is also good news.
However they could also could go Airbus with the A318, especially on high density Belfast London and London Paris/channel islands routes.
Whatever route they do go I presume the Avro RJX was what they were looking for, but at the same time the 146's currently in service still have plenty of flying hours in them yet!!