Havent fished Margam but knowing the area at least you'd have some nice surroundings even if the fish werent biting.I've heard the odd snippets about it and there are some good bream to be had. I believe it fishes slow when there's been alot of rain(but then again doesnt everywhere). I'm not sure whether Maesgwyn is still open for coarse fishing as I understand it's either been sold or in the process of being sold.However I wouldnt go out of my way to fish it especially as they were charging 10/day to fish a muddy hole not much bigger than 2 tennis courts stuck together.Still if you're desperate for a catfish and like tennis I guess you might consider it.
I Fished Margam park about 3 yrs ago ( on a rare occasion that Dooby ( my son ) beat me) like anyexcuse says there were some nice surroundings. There are 2 lakes but at the time u could not fish the lake by the house shame really cos there is some nice roach in there. The lake we fished was by the caravan park manly Carp some small skimmers but Dooby had some nice big Tench out of there. U book in and pay by the entrance and it is one hell of a walk so u want to travel light and not carry a shed full of match gear. If u want i can nip down there and get the full details for u, Phone No etc just let me know.
I live half a mile away from Margam, but very rarely fish it!
There are some good fish in Furrs Mill which at the moment is the main lake, my advice would be - go there mobile, be prepared to walk around and stalk the fish. There are some bigish Carp in Furrs Mill upto 18lb I think, quality Roach if you can get them to feed, and Tench upto 5lb, some good Bream have also been reported but I personally have not seen any of them. On the subject of Bream, if you want to catch real quality "Binlids" ask at the kiosk if you can fish the top boating lake, if the ranger says yes then pay for your ticket, go back out of the Park and turn right as if going back to the M4, after about 100 yds turn right to the Orangery, follow the road until a fork, take the right hand road and continue until you come to the boating lake. You'll see a car park right next to the water, this is where to fish as people regularly feed the ducks here with bread, fish a slider at about 9 meters out and feed heavy with groundbait, corn, and bread. My personal best here is 48lb 6oz for 8 bream and they all came like peas in a pod!