hi kinsey - what a great move, and all that space too!
At this time of year especially when the ground is frozen or waterlogged, there's not a lot you can do out on the veg plot. Most sensible people have already dug over the beds in autumn and then stay indoors and plan their crop rotations and buy seeds, maybe start a few seeds off early such as onions or maybe some basil on the windowsill just to be feeling they are doing something.
If I was you, I'd be repairing the polytunnel and getting the greenhouse ready for the coming months. I don't know anything about growing conditions in Shetland but I imagine those 2 will get a lot more use than the outdoor plot in the early part of spring. They'll be warmer so extend the season by allowing you to start seeds off/grow on under cover until it is warm enough to start moving them outdoors.
The veg plot - there's plenty of advice (
http://www.allotment-garden.org/garden_month.php) Usually it is clearing the weeds, digging to break up the soil, adding manure/compost and planning where things are going to go. Good luck with the plot - it sounds idyllic