I live in Brighton and I have to say that the quality of the fish and chips shops that are actually on the seafront itself is not great (there's a Harry Ramsden's that I've not been to that always seems packed, so that might be exception).
To find the best f&c in the town, you have to get closer to the centre. However, it's certainly true that it's a lovely feeling taking them down to the beach to eat - if you don't mind being pestered by seagulls.