Depends on which tubers let us know which and we should be able to help

If you mean dahlias then wait till the frosts have gone. In other words wait till spring.

Probably a bit later with Begonia tubers. Fall with Cyclamen tubers. Others would be better answering about potatoes in the UK. If we knew about where you gardened in the UK, we could give more specific dates, but it's all dependent on the weather, anyway!