The book you have is an excellent one for the Islamic political narrative of that period. I see the book cited quote often.

For Spain, I would also recommend for a more scholarly look Early Medieval Spain: 400-1000 for a general overview and the Arab Conquest of Spain 710-797 for a specific look, both by Roger Collins.

Collins' Visigothic Spain book alone is considered the gold standard in history for the time period, which establishes the political framework just before the conquests and also revises previous thoughts about the perceived weakness of the Visigothic regime beforehand.

But if you're just looking for one book to cover the breadth of the from Visigothic to Umayyad, Early Medieval Spain is it.