Many thanks to SWLing Post reader, Colin, who writes:

This chart may be familiar to some, for others like me who has just found it, this will be a very useful one-stop information page for UK spectrum allocations for scanning the bands.

http://www.ofcom.org.uk/static/spectrum/map.html

Thanks, Colin! Ofcom has done a fantastic job making this data accessible. Individual maps for each chunk of spectrum can be downloaded as well.