I think a Gulf Traveller route from BHX will be more successful than a route from MAN for a few reasons.
Firstly lets look at who flies into BHX and the operators at the more exotic end of the Spectrum include Mahan Air, PIA, Emirates, Air Slovakia, Uzbekistan and Turkmenistan. The last 3 of those airlines operate out of BHX to provide a transfer route via their main base to the Indian Subcontinent. These passengers are not interested in premium cabins or airport lounges - they simply wish to get from A to B and on time - which can be an issue with some of the CIS operators!!! The idea of a no premium cabin fits exactly into Gulf Travellers concept of an all economy product
The Gulf Air brand has been around for a long time and is well known. Abu Dhabi is a delight of an airport (I was there earlier on today!) to fly from or transit through and the way it is expanding will mean that passengers from BHX will have a big range of connections available to Asia and Africa and this will appeal to the ethnic communities in the Midlands.
If you had the choice of flying with Turkmenistan and transferring through Ashkabad or flying with Gulf Traveller and transferring through Abu Dhabi - then Gulf Traveller would win hands down!