Being in Dumbartonshire I'd have thought possible temperatures similar to myself, I'm Scottish border . I can't put pots outside until may /June. I have a greenhouse unseated and start seeds off indoors on windowsills at steady temp, turning them daily for light etc. not ideal but it does work for me.
We still have some winter ahead yet up north, could you put your herbs on kitchen window sill ? Do you have one that gets some sun ?