Kidderminster was always my favourite track when I did nationals;
Back then the only part that was astro turfed was the main straight.... looks like the same stuff still exists!! The thing I love about the track is the combination of surfaces mixed with raised/lowered transitions giving varying grip levels & interesting gradients which are in-keeping for a 1-10th scale car - not the massive ramps/jumps that we often find on tracks these days, that are fine for the skillfull & the brave, but can prove damaging & expensive for the less experienced. Kidderminster's layout flows nicely too & the features are almost 'organic'.
Another feature that I remember was a sweeping, banked dirt 180 deg curve at Batley (I think) that was a real buzz to drive - maybe this is something that could be built? In the event of a wet meeting (or to preserve it) an alternative route could be marked on the flat grass on a tighter inside line?
Even if you manage to emulate such features in a couple of areas of the track it would really add to the racing experience.
Edited to add; I do actually really like the track as it is - the layout was better last night than it was two weeks ago.... that if you can see it!