I have about 150 trees, all sizes and stages of development. I have been growing for 20 years plus now. My favourite species is Larch, I have a lot. I do like deciduous, and I have a lot, Scots Pines too.
It must be quite difficult on the coast with salt water spray, especially when you get east winds blowing.
If you go into any garden centre you should find fleece for frost protection. It comes in a roll. As an alternative newspaper over the leaves will help. If you look in Amazon you should find it as well.