Advice for a newbie, please ...

Hello. I'm a newbie here, come for some advice about perennials (and, in due course, probably lots of other things ...)
Long story -- short: My mother died this summer after a stroke, leaving me the house which has a biggish, overgrown garden. She was always an enthusiastic gardener, right through her life, but when she got into her 80s. it all became too much for her and she concentrated - with my help - on the fruit and veg.
I need to sell the house and find somewhere smaller - but first I have to do something to tidy up the garden - nothing too adventurous - just enough to make it look presentable and attractive to a prospective buyer in the spring/summer of next year.
I've cleared the worst of the undergrowth, liberated a rockery. done a bit of landscaping around the pond and ordered spring bulbs, heathers, annual seeds and some perennials as plug plants, which I have repotted and am growing on in the polytunnel.
My question is this: I live in the north west of England - on the west coast of Cumbria. The wallflowers, pansies and primulas are coming on nicely - others like aquilegias, campanulas and salvias are still quite small and tender and have a way to go yet ... When do I plant them out into their permanent positions? Everything I read says I should be doing it soon ... but won't they be damaged if we have a really cold spell - or are they hardy enough to withstand frost and snow? (Not that the west of Cumbria tends to get much snow - or very hard winters, but it has been known.)
I know it's a very basic question ... but although I'm quite comfortable with fruit and veg, I'm a real newcomer to flowers and I really feel a bit confused and in need of some guidance.
Posts
Do you have access to a porch, greenhouse, cold frame etc.
Hi Mickledore
I don't think I'd plant out anything from a polytunnel at this end of the year,
In the sticks near Peterborough
Hi Mickledore, sorry to hear of your loss. It's always difficult to do this sort of thing. If I was you, I'd leave the small plants. I'm in west Scotland and our climate is quite similar to yours. The plants are all hardy enough, apart from maybe the salvias, but they're likely to get drowned over winter more than anything else. Pot them on as they grow, and in spring, if you're ready to put the house on the market, and the growing/weather conditions are quite good you can plant them out as they'll be a better size. You could also just sink the pots into the ground or tuck them behind other plants where possible, to save too much effort - there's enough to do when trying to sell a house. I'd leave the salvias in pots and be a little more cautious with those - wait till the weather's more favourable if possible.
I live in west central Scotland - not where that photo is...
Firstly welcome, you've come to one of the best places for free help I have ever known.
So far you seem to be doing all the right things so carry on what your'e doing.
As for the perennials, if they're as small as you say then I would leave them overwinter in the polytunnel for winter. they need a good root structure to thrive and I would guess they still have a way to go before getting there. When the roots fill the pot they'll be ready to plant out, and over the next month they should get somewhere near that point before going dormant in the winter. By that time the ground will have cooled significantly and so putting them then would increase the likelihood of losing them. When the days start to lengthen in April next year, as long as the ground isn't frozen then you can consider planting them out, so keep an eye on the weather.
Planting out in spring can be hazardous as unexpected cold snaps can do untold damage to newly planted out perennials, so look for a longer warm spell next year, even a few weeks of warm sunshine can give them a better start.
When it gets to that time, don't be afraid to ask for help on here, the only stupid question is the one that isn't asked.
Right now I would improve the soil in which you intend to plant them, will some well rotted manure. This will rot down over winter and give them a good start when they do go out.
Best of luck.
Thank you, everyone. That's all very reassuring and very helpful. My instinct said I should keep them protected in a cold polytunnel over winter ... but what I was reading (including the blurb that came with the plug plants) seemed to be saying otherwise. I'll need to buy some more pots and compost, but I have the manure (found it in a plastic sack - that was a surprise - it's well-rotted with a vengeance ) and quite a lot well-rotted compost in the bin ... so I'll get that onto the beds out front and the rockery.
And I'd thought about actually keeping some of them in their pots and just burying the pots ... so I can take them with me when I go. (IF I go ... houses aren't moving too fact around here at the moment.)
I'm feeling a lot less confused now.
PS: Fairygirl - I'm actually looking at the west coast of Scotland to move to ...