In reply to dylanwall2388:
As a veteran of many European winter road trips, I'd say your safest bet is probably to stay in Spain. Southern Spain has one of the best winter climates in Europe, and if you are lucky with the weather you can also take in a wide variety of different areas further north in the country.
Siurana and Margalef are some of the best places in Europe to hook up with other climbers - they have good "van scenes" and climbers' campsites. However, at the time you're travelling they can be pretty cold unless you get lucky. Chullilla is a bit warmer, and also has a good scene, but the best routes start at about 7a (5.11d/5.12). The Costa Blanca has the best weather, but the climbing scene tends to be quite dispersed unless you stay somewhere like the Orange House. El Chorro can be deceptive - it's a long way south, but it's mountainous, so the weather is often worse than the Blanca.
Leonidio might also be a good bet. The whole area is a big suntrap, and there is a climbers' bar and a climbers' campsite for meeting partners. But even if you take in other nearby winter venues such as Nafplio, you won't get the variety you'd have easy access to in Spain.
Southern France and Finale/Oltre Finale are great areas, but very unreliable for Dec/Jan - you'd have to get very lucky with the weather.
Our blog might give you some ideas
https://rockaroundtheworld.co.uk/category/greece/leonidio/
https://rockaroundtheworld.co.uk/category/spain/