Brooding needs pollen. One frame brood needs one frame pollen.
In UK they have pollen in nature almost the whole winter, but bees need sunshine and 16C temp that they may forage it.
Even if bees fly in the temp of 6C, don't believe that they get yield.
If you have a bee strain, which does not react on arriving winter, it continues so long brooding that pollen stores are finish.
No hive can continue then.
For example if we in Finland use New Zealand queens, they propably will die all next winter.
One guy here told that he bought 10 package hives from NZ and they all died next winter.
You have the same problem in Alaska when you bye from Hawai queens. They affects to local genepool and they surely have not local shedule.
Our researcher took 10 Anatolian queens. After 2 winters all were dead. They had no brood in winter but their general winter consumption was double compared to local bees.
When colony has a good winter sleep, they are in good condition when true spring arrives. If hives are restless during winter, quite much will be destroyed when they try to do something all the time.