I’d be tempted to stay further east than Gower etc. Gower is slow to get off and the riding isn’t that good (although it is stunning). I’d go for somewhere more Abergavenny way, you can ride Cwm Carn if you want, then you’re well placed for the main Black Mountains riding, and evening stuff like the Blorenge. Not too far to head west to the Gap etc.
Brechfa and Afan are fine, but in July you really want to be doing most of your riding around the Black Mountains I’d have thought.