Temperature advice please!

Due to unforseen circumstances my spare bedroom will be occupied this Easter, so my newly sprouted toms etc will have to be moved to the potting shed
My seed potatoes will have to go out there as well.
I have an electric fan heater I can use - at present set to frostguard to protect my potatoes in a pot.
So any suggestions as to the minimum temp I should set to help them survive the weekend will be gratefully accepted.
They can come back indoors on Tuesday if necessary!
Cheers
Elaine