This is a tough subject to get deep into because Visigothic Gaul and in particular the role of Toulouse is thinly in evidence in written history and archeology. Most of the work that exists is very academic and only found in deeply stocked libraries.
However, this book is a comprehensive bibliography of publishing on the subject of Visigoths in Gaul and perhaps you'll find something that tweaks your interest in it:
The same author also publishes updated supplements such as the 2007-2009 Supplement (Brill, 2011) where you may find the latest scholarship.
You can find a lot of the bibliography listings in Google Books and you might find something in English, but a lot of it is German, French and Spanish.
Ferriero also edited The Visigoths: Studies in Culture and Society (Brill, 1998).