I’m driving to Port Talbot and will have my bike and 2-3 hours free this afternoon.
I haven’t been to Afan for a few years, so was thinking of doing the Whites Level Trail.
Anything else I should consider?

Well yeah Afan seems the logical solution, there is other stuff about that area, but with only a few hours free.

White’s, Wall or Penhydd. Blue Scar is too short, Blade possibly too long if you need to be out of PT and back again in 3 hours.

I would park at Margam country park and explore. have a look on Strava for ideas.

Depends how strict the 2-3 hours is. The wall is the quickest if you park here:
https://www.google.co.uk/maps/@51.6338083,-3.7351779,3a,75y,82.49h,73.87t/data=!3m7!1e1!3m5!1ssPWWnjMQCt3ASaNixO9DZg!2e0!6s%2F%2Fgeo2.ggpht.com%2Fcbk%3Fpanoid%3DsPWWnjMQCt3ASaNixO9DZg%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26w%3D203%26h%3D100%26yaw%3D17.272127%26pitch%3D0!7i13312!8i6656?hl=en

Just make sure the bike is very securely locked up while in Port Talbot 😉

Are there any marked trails at Margam?

Me and a mate did a 6 hour endurance race there a couple of years back and I’m sure there were trail centre type sections. They were quite good fun

there are some really good natural trails nearby if you prefer steeper more technical stuff. email me if you want more info