Defending one bit of coastline doesn't solve the problem, it just moves it slightly further down the coast. It's inevitable that some places will be lost, like some have been lost before.
This is an excellent point. It was decided to protect the village of Mappleton on the East Yorkshire coast because the main road through it passed very near to the eroding cliffs. They built a rock revetment to protect the cliff and two large rock groynes to trap the sand, which would diminish the waves’ power.
Of course, the cliffs down the coast, now deprived from the sand protecting them, eroded at a much faster rate, leading farms to be abandoned.
I am sure that everybody who did GCSE Geography after 1990 will be familiar with this.
Unfortunately, I am not sure what the exact circumstances at Fairbourne are.