Can I or should I plant bare root shrubs and roses, even though a frost is forecast for Thurdsday night?

i think the following advice will be true for all of what you have, but sure it is right for the Roses, i bought quite a few bare root roses last winter from the David Ausin web site, all of which arrived during the winter period, which is the best time to plant. i rang up customer services department to check the very same, and was told that yes you are fine to plant this time of year, but obvioulsy not when the ground is frozen, you can buy a root treatment from the DA web site that will also help, i would wait until we get a milder spell, i believe most parts of the UK have rain forcast next week so temp should be slightly milder, and plant then, soak the roots in water overnight before planting - obvioulsy somewhere cool, but not likely to freeze or get frost. make sure you plant roses deep, the bud knode needs to be just under the soil level, water in well and top dress with mulch, and all should be lovely in the summer. would normally say good luck, but don't think you'll need it lol .

I would not recommend planting them if the ground is frozen as digging the hole would mix the frozen soil with the non-frozen bringing it into contact with the roots. If the soil however is not frozen then planting is ok. If you do plant and there is a frost forecast then while the soil is frost free then mulch as you say with a good thick (4 inches at least) layer of whatever. The top growth of deciduous plants is dormant now and not harmed by a normal cold spell. All the shrubs you mention should be ok.
Bare root plants like this will keep in a damp sack in a dark frost free, but cool place for a few days without coming to much harm, as long as the roots do not dry out.

Whoops, cross posted. At least we agree!

lol - obvioulsy good advice Owdboggy!

If you have somewhere that thaws during the day you could heel them in until better weather comes. Dig a trench with a sloping side and lay the plants at an angle and cover the roots with soil. Tread lightly over soil with your heel to press soil lightly round the roots. Cover with sacking etc if its really cold. Carefully dig up and plant as normal when weather permits. At Standen we had hundreds of young hedging plants heeled in all winter while we planted them a few at a time, every single one survived and grew last summer.

Brilliant, thank you so much. I'll post the pics in Spring to show you how they're doing. They are temporarily planted and tucked away from the frost, which looks like a bad one tonight, so I covered them with an old rug so they should be snuggly under that.
Thanks again so much.