sandy beaches help prevent coastal erosion because they slope into the sea, and reduce the effect of wave action. Coastal erosion is a highly complex subject however, and you will be well advised to seek professional help before making any purchase decisions.
When the ice from the last ice age began to melt and retreat, vast quantities of mixed material were dumped into what was a big sea bay in the area, This material was deposited on what's called a glacial outwash plain, and it formed the land that is the Holderness plain on which Bridlington stands. The material is composed of sand, clay, small stones and larger stones all mixed together,and it's this which is being eroded by the sea. Effectively the sea is steadily taking back the bay that was filled in ten thousand years ago.
"might have to change my login name when I move." Scunthorpe is safely far enough away from the sea to escape coastal errosion, and locals affectionately call it 'Sunny Scuny', that has a nice ring to it...;)
Incidentally over the years local TV and papers have covered many stories of people whose properties have slipped into the sea 50 years before the expected inevitable slip. There are no guarantees even with professional opinions, nature can go it's own way on a whim. I wouldn't want anything nearer than a mile from that coastline.