GASML
I think you may already have this URL, but I’ll put it here in case anyone else is interested. – http://www.hertsflyingclub.co.uk/.
Brian Curtis, who runs the strip is very friendly.

From the website:

The club operates two grass strips,
050° – 230° by approx 350 yds long and level
140° – 320° by approx 275 yds long with a slight slope, 320° end lowest.
Both are wide with a good approach.