@Former-Member I haven't tried seaside gardening myself, but what I've read from other gardeners is that the biggest challenge is that everything you put into the soil quickly washes out again. I've heard of some gardeners adding clay soil to their beds to help hold water and nutrients, and as a short term measure, I've heard of people digging a pit, lining it with newspapers (to slow down the water) and then infilling with soil, compost, manures etc.

General rule would be to use things like manures for fertilising. Soluble fertilisers or liquid fertilisers would wash out too quickly. The fibrous stuff that is in the manures acts like a sponge to hold the nutrients in the plant root zones for longer.

Look for any plant that has "coastal" or "sea" in its common name. Seaside Daisy (Erigeron), Coastal Banksia, Sea Kale (a vegetable, but also gets spectacular white flower heads), Sea Lavender (a type of statice). Also, once you've moved, make a point of going for morning or evening walks around your area, and pay attention to what grows well in other people's gardens, and in public gardens. If there's a town botanical garden anywhere near the coast, that will be a jackpot of information, because usually they've got all their plants labelled. If they don't, you should be able to find a gardener to ask.