650m concrete available at Upfield, but obviously no IAP's etc. Open airspace too (well below 4000' anyway), plenty of room for overnight parking. Landing fee £5, no parking charge.
As Flower says, published procedures into Cardiff are fairly straightforward, and ATC are very GA friendly. As you're (presumably) coming from the NE, expect to be routed via Wenvoe or Cardiff docks VRP's so revise those. Get yourself "handled" by the flying club to avoid extortionate handling costs - landing fees should be around £20, no idea about parking. (Obviously this limits you to arrival/departure within club opening hours)
Approximately half hour taxi ride from Cardiff or 35 mins from Upfield into Cardiff City centre, alternately use train from Rhoose (Cardiff) or Newport (Upfield)