The social life in Spain can be as hectic or as slow as you like! The Spanish love socialising and meeting up with new friends and renewing old acquaintances. Whereever you go in Spain you will find an expatriate club to join up with and speak your own language. However, if your purpose in life is to integrate completely into the Spanish way of life, that is easily achieveable as well.
You will have a better lifestyle if you at least learn some of the language. Spanish is a very musical language and easier to learn than some of the north European languages. The Spanish will welcome you with open arms if you try to learn and will always help you. Whether you live in a remote village in the mountains or in the centre of a big city, you will never feel isolated if you make an effort to converse in the local language.
There are many clubs of all types in all parts of Spain, not to mention clubs such as golf clubs and international clubs, even the British Legion, so you can feel "at home" while on Spanish soil. This is great for people who retire out in Spain and who may be left on their own when their partner passes away. They will still be surrounded by friends.
For the younger generation, the club and bar scene is an inherent part of Spanish life. There is always music and dancing going on somewhere in your area. Opportunities for work can be limited if you do not speak the language, and it is not as easy as just coming to Spain to work in a bar (even temporarily). You will be expected to pay into the social security system.
Whether you live on the coast or in the countryside, daily life is much the same in Spain as it is in the UK. Chores still have to be done, but there is something about going shopping in the sun rather than in the wet and cold weather of northern Europe... so I guess we are back to the weather again! People are more likely to communicate in Spain. A simple "hola" can start up a conversation about all kinds of things of interest, or a chance discussion in a bar can set you off in a completely new direction in life. Going out for coffee or breakfast is common place in Spain. In Madrid it is mandatory! In the UK we have happy hours and the tradition of going for after work drinks on Friday nights, in Spain it is normal to go out for coffee to discuss business. It is much easier to make friends in Spain - people talk more and are more likely to strike up a conversation for no apparent reason.
All in all, the lifestyle in Spain is good.. Come and join those of us who have taken the plunge!