Given the cool climate of Scotland, you are better off not growing
basil or rosemary (or sage). I am fairly sure thyme, sorrel and mint
will make it there, and they are perennial and productive. Parsley
needs reseeding every year, so if you don't mind the extra work, go
ahead and plant that too.
Chives and oregano will make it there as well, chives may need
reseeding. A few large containers should give you herbs for the whole
year.

I have rosemary now (which I bring indoors for the winter), but around
here the workhorse herbs are mint, sorrel, oregano, thyme, and parsley.
I have sage, we are right at the northern limit of its range, and grow
some basil, enough to make a jar of frozen pesto for the Fall. Thyme
and oregano work well in the regular garden as a ground cover. Thyme in
particular can make an attractive cover. Thyme will dislike shade but
oregano adapts to some shade as well. If you can establish them as a
ground cover, you can use your containers for other herbs. Sorrel and
mint will take some shade. With this in mind, you can try some herbs in
the ground and see if you can use the containers for other herbs.

I never use my dehydrator with herbs. Herbs for the kitchen are chopped
and frozen in airtight containers (the smallest ziploc bags will do).
Herbs for tea are dried on newspapers in a spare room (out of direct
light) over two weeks, and then stuffed in airtight jars.