I don't know the full details regarding the closure of Upfield Farm but I understand that there was an issue regarding planning for the hard runway backed up by a NIMBY campaign.
As regard getting some lunch from Cardiff. You could always go for a local flight and eat at the Flying Club. Shobdon, as you mentioned, Swansea is ok or Pembrey (weekends only). Cotswold (Kemble) has an excellent restaurant. If you want to go a bit further afield then Haverfordwest is a nice destination or cross the water to Dunkeswell.
There's some stunning coastal and mountain scenery down this way and it's well worth making the most of it wherever you decide.