To the north of Friday Street and towards Polegate, Stone Cross and Pevensey are fine, the lower Langney area is a bit more undesirable. The Hydeneye area of Hampden Park is probably best to avoid.
Some arts of Hampden park are nice, and some parts of Langney are too. There's some housing estates in both areas that aren't as nice. A close friend was brought up in Hampden Park and loves it. My ex lives in Langney and has no issues in his area either.
You better get your coat mate, you simply aren't allowed to say anything against Seaford round here. I've learned my lesson. You simply just have to pretend so as not to offend.
Old Town balances not too expensive but good area, so good value for money. Meads, Ratton, Willingdon, Polegate, North Harbour, Stone Cross, Pevensey, Westham are probably the best areas. On large give the Shinewater/Langney/Hampden Park areas a wide berth.