In reply to teodude:
If you're coming anyway and genuinely, nationally mobile. Don't make a plan, just collect some ideas.
Most of our bigger climbs are mountain areas, most of our sea cliffs are on the wetter west coast, they get all the cool, wet, windy weather coming in off the at Atlantic this time of year.
That said, it's not all Atlantic storms and we do get weather systems where part of the country gets much better weather than the rest. I'd be prepared to head way up North to the Scottish Islands/coast *if* they're getting good weather or more likely way down south, Dorset, Devon, Cornwall or Gower and Pembroke. They're a whole day of driving apart so really it's one or the other.
Cairngorm climbing clings to the hillsides, unless anyone can confirm otherwise I'd assume a lot of it is already wet with seepage and autumnal Scottish mountain weather. It won't be in winter condition unless there's a freak cold snap.
The Lake district is lovely, perfect for what you want but notoriously wet. Avoid unless you happen to hit a freak warm sunny week.
North Wales gets a lot of weather but there are better and worse crags for it. Gogarth, Holyhead and Tremadog can be dry when the mountains are in the cloud. The Llanberis slate dries fast if there are gaps in the weather. The mountain routes hold onto the damp and many seep.
There's the Peak District and Yorkshire where there is almost always something drying up between showers but it's mostly short outcrops. There's some great stuff but it's not the season for a short trip to it.
If you're not coming anyway, I'd reschedule for summer and plan a road trip to take in some of the best bits or explore a remote area.
jk
Post edited at 12:28