Europe, although a rather small continent, hold a wide variety of surf spots and conditions. In the northern countries, you have to wear a wetsuit all year around, while you only have to wear a wetsuit in the winter month, the further south you go.
In the summer month, famous spots at the Atlantic coast such as Biarritz in France, can get pretty crowded. If you're traveling with a car or bus on your own you can avoid crowded spots.
Although winter month may have great waves at the Atlantic shores caused by storm from further north, you wont't want to hit the water without a thick wetsuit - probably 5 mm. The only places where you can get away with shorts and a rash guard or a thin wetsuit are South Spain, South Portugal and the Canary Islands. However, flights to the Canary Islands are usually more than 300 € nowadays, especially if you want to take your board with you.
Most surf camps, surf hostels and other surf accommodations in Europe are located at the atlantic shores of France, Spain and Portugal. This is the place where you want to be if you're looking for a good combination of surfing and partying.