newbie in Snowdonia advice please

Hello everyone
Can anyone offer me advice on what I may be successful with here in Snowdonia. We live at 1300ft, I have begun to renovate a fruit garden with blackcurrent well established, raspberries have all died off in the last couple of years but the land gas become very boggy in some parts of the garden. The garden gets full sun, is south facing and has wind protection with trees behind and on both sides.
I have just started a veg garden with some raised beds but mostly will be planting direct into he ground. My soil is heavy and stony, lots of slate here. I bought some plug plants for autumn planting brassica collection and have already lost lots us to slug damage please can someone advise the best way to get plants established?
Ideally I am aiming for some degree of elf sufficiency year round, looking to plant potatoes, onions, leeks and some greens.
Looking forward to being part of this community 😊

I have a very exposed site and, while I don't have one, polytunnels seem very effective for my neighbours.

I also use all raised beds as very clay stony soil.  And a no dig lots of mulch method - google no dig and lasagna planting.

I look for varieties that are short and sturdier. And use scaffold netting to provide some extra wind protection and cloches to start stuff off earlier.

I have a greenhouse at home to bring things on earlier too then transplant them when they are quite large.