Musically, really very little. If there's a dozen decent music pubs in the area described I'd be surprised.
I think you're down to one pub in Harrow, a couple in (North) Greenford, maybe one in Ruislip, not sure about Uxbridge - there used to be several but precious little left now. That's the A40 done.
The M4 corridor is not much better. A couple of pubs in Brentford & Isleworth, a couple in Hounslow, and a couple in Hayes.
The only area where music pubs seem relatively healthy still is the triangle below Heathrow stretching down to the A316.
It's not great. I'm sure things improve once you get outside the M25 though.