We are about 1200ft up, here in the Derbyshire hills. like you, we have long winters, snow, and gale force winds. The soil does not warm up until around mid May. I have visited friends further south, and their veg and flowers are harvested nearly as we are planting. As for tomatoes, I have given up, as we never seem to have the nice summers to ripen them anymore.
Most veg can be grown in containers, or things like builders sacks etc. if you only have a small space. Even hanging baskets, and wall troughs can be uilised. +-+ It seems to be hit and miss here, as to how well things grow, what with the weather, and wet summers we are having. I cannot see you having a problem with the salad stuff. I would plant a little of what you like to eat, and see how it grows, and if it comes good, you will know for next year.
I was pleased with my potato crop last year, and the cabbages, and broccoli, leeks and spring onions also. I vitually left them to their own devices, as I was so busy elsewhere!! I always do well with early onward peas, getting a bumper crop......but with being tall, there is always the risk of the weather and high winds wrecking them. I tend to try and plant them behind a hedge!!
I am hoping to do kale, kohl rabi, and celeriac as well this year. Not a lot, just to see how they grow here.
My neighbour up the lane always had a successful brussel sprouts crop, but for some reason they were a disappointment for me.