Weirdly I found myself googling something similar earlier to scout out new locations. If you put in your criteria into google it recommends
Bridlington, East Yorkshire
The Vibe: A traditional coastal market town featuring a working harbor, two sweeping sandy bays, and an historic "Old Town".
Newbiggin-by-the-Sea, Northumberland
The Vibe: A soulful, small coastal town built around a sweeping bay. It features fresh air, sandy walks, and an iconic offshore sculpture
Ayr, Ayrshire, Scotland
The Vibe: A classic historic coastal market town boasting a beautiful beach, rich Robert Burns heritage, and excellent local high street shopping.
Workington, Cumbria
The Vibe: Situated on the gorgeous Solway Coast, this traditional market and coastal town serves as a great gateway to the western edge of the Lake District.