It's an area I know well as we go up to visit the wife's family who are in Newcastle
As others have said Tynemouth is really nice but basically anywhere along that coast will be nice. If also recommend Seaton Sluice, Cullercoats, Blyth and even Whitley Bay is very nice. Depending on your budget you will even find parts of North Shields too will get you huge Victorian villas close to WB for not much.
Further up the coast places like Warkworth are stunning - on a summer's day it's a picture perfect English town. Amble, Hexham, Alnwick etc are all good too. Yo be honest if you stay away from the "rough" parts of Newcastle close to the town centre you're generally going to be fine. Even then I personally never find them as rough as the areas around Manchester.
Northumberland is a hidden secret - huge beaches, very quiet, cheap and an amazing lifestyle. Good luck and you will enjoy the house hunting!!