Yes, to improve, this should have a UKA licence for future races. This will give the race a better standing, and for anyone needing a fast qualifying time for other events, this could be perfect.
As a local (I had a nice 1 mile jog to the start line), I didn't see a great deal of publicity around, other than for the road clossure signs, so not surprising that there weren't 100's of local out their.
As for the subway, it has to be done to get under the A4. I guess it is just too close to the start for the race to have thinned out. An extra mile or so on the town side of the A4 might help.
Personally I thought it was a great event for Maidenhead and Purple Patch to host. A few more minor tweaks for year 3 maybe.