overwintering question..

you can but i would only light it when frost is actually forecast. and dont forget to ventilate it in the mornings if you can. are the plants frost tender then? if they are fully hardy they wont need the heat at all.

I have a couple of open/close vents that i,m going to put in.
some are shrubs, a couple of hardy fuchsia's, baby astilbe's and going to try to keep some cineraria, osteospermums and primulas.
amongst others.

I am sure that you must have a small area of spare garden in which you can dig a trench and 'heel in' the plants until your bed is overhauled. They can be packed together for one winter as long as they are planted properly in spring.
If you don't have any 'spare' garden then I would use one end of the bed that you are renovating.

I have a raised bed I use as a nursery bed, would it be better to put my shrubs and hardy's in there over the winter instead of in the shed?

Short answer 'yes' shrubs do not like being stuck in a shed - even if it does have light - for several months.

By the sound of it, most of the things you want to keep will be fine in pots until next year, with the exception of the fuschias, osteospermums and cineraria. If the fuschias are hardy, heel into the soil and cover them with a mulch or some kind of protective covering (not plastic) - I say this only because you live in Scotland! If they're tender, it would be better to put them in a frost free place, along with the cineraria and osteospermums.

I would rather keep my shrubs in the pots till next year. I can move them to a sheltered area and cover the pots with fleece if that would keep them safe.
the fuschia is a hardy type, it,s small enough to heel in and cover.

Only reason you need the fuschia in the ground is they can be killed in pots because the roots are frost sensitive. And you don't need to cover the hardy shrubs and stuff with fleece, just cluster them all together - the only time you might need extra protection for them is if the temperature drops below zero for longer than a few days, say minus 4 constantly - that might mean the pots would freeze, but that's pretty rare in this country.

cheers Bamboo that,s explained it clearly enough, thanks.