Hello Patrick
Whilst I can't offer you any useful advice from personal experience, it looks as if the GR7 follows part, if not all, of the E4 European long distance path which goes between Tarifa in Andalusia and Cyprus.
From a Google search, there are several possibilities of downloading free GPX files for the Spanish section of the E4 (wandermap.net is one option).
Whilst I can't guarantee the accuracy of any files or routes, it might be an option for you to pursue.

My wife and I are considering walking the Andalucia section of the GR7. I have just ordered a copy of the (now out of print) Cicerone guide book. However, I am told that the route isn't always well marked and would like the added comfort of having a decent map.

So, does anyone know where I can get such a map and also is there anything downloadable to my phone?

Many thanks in advance.

Patrick