I agree with Kolibear. It's so close to Welwyn, it makes no sense not to give it a try. I haven't seen the aforementioned "TFC" around that much recently, so he's probably nothing to worry about.
Make sure you ring in advance, and if it's busy you might have trouble getting a response on the radio, but keep trying!
It's a longish grass runway. Watch out for noise abatement procedures, and turbulence over the trees on 29 approach, put otherwise pretty straightforward. I always find it a bit tricky to spot from the South, despite flying from there for 3 years, so be careful not to fly right over it and into Luton CAS!