On December 21st, just after sunset, Jupiter and Saturn will be visible just 6’ apart. This very close conjunction was last seen in 1623. Even if you can’t see them on the 21st, you can still see them very close together on the few days either side of the 21st. On the 17th they will 28’ apart on the 23rd they will be separated by 14’.
The image below shows them on the 21st at 17:00GMT from Abingdon.
The down side is that they will be very low, not even 10 degrees above the horizon, so you will need good clear horizon to see them.