Excellent bit of work hats off to you. Is there a good place to take pictures??
Stayed at the caravan site at Pembrey Country Park 2 weeks ago and headed off on my bike to investigate the range.
It is possible to ride through the park (forest) to the beach and then ride down the beach towards the range. An easier way is to head for the racing circuit and then cycle down the disused runway (lined with old tyres) between the circuit and the airfield, turn left at the end (there's a gate to your right with a sign saying 'no entry active airfield'), stay on this road/track all the way to the beach. If you look to your right when you get to the beach, you will see the range control tower and if the range is active you should see a yellow caravan in the middle of the beach about a mile from where you are standing, this is where the range lookout is. You can go right up to the caravan, but no further. You can also walk up to the dunes here to look onto the range, but don't cross the imaginery line behind the caravan or you will get a visit from the law. When I went there sod's law came into force and nowt turned up. Earlier in the day 'Snapper' flight was using the range and turning right over the caravan site. I'd imagine a 300-400mm lens would be o.k. here to catch the aircraft coming off target. A chat with the guy on lookout (very approachable) revealed a Merlin in for a refuel and that it had been using the range until midnight the night before. Did'nt here a thing in the caravan though - too many pints of Brains SA!