I am not aware of any book that covers the topic you mention. I can see it is a difficult topic to cover especially at pre-intermediate level.
I’m guessing that by learning unit you mean a series of lessons. I hope this is right. I suggest you make the unit project-based. In the first lesson you could show the students various flags and the outlines of countries from a map. Ask them to tell you what the countries are. Ask them what the countries have in common – they’re all European. You could leave out some of the European countries and ask students which countries are missing. You can also ask students to list as many European countries as they can; alternatively you could use this as a warmer in another lesson.
You could then put the students in pairs or groups and ask them to discuss the following:
Have you ever visited / been to a European country? Which one(s)?
Do you speak a European language?
What do you know about Denmark / Spain? (limit students to 2 or 3 countries).
Do some whole class feedback on the above. You can then talk to them about what they know about Europe, why it is important to know about our European neighbours. Some of them might have pen pals in one of these countries. Ask them if they think people today have more knowledge of these countries than their parents. What are the reasons for this – EEC, more travel, increased cooperation in business, etc.
Tell them they are going to do some research to discover whether young people today are more aware of European issues. They will interview people of their own age, people of their parents’ age and people of their grandparents’ age. Interviewees can include other teachers, neighbours, as well as family members. Students then spend time in groups writing the questions they want to ask. Go around and help where necessary. Allow students some time to plan who and how many people they will speak to and to plan how they will record their results. Tell them they are to do the interview in English as much as possible.
In a subsequent lesson, allow students to write up their findings. This could take the form of a poster, a graph, a table; whatever they prefer. Tell them they will present the results of their study to the class and allow time for preparation. Pre-teach the language required; probably comparatives, e.g. they knew more / less about…… Phrases such as half / more than half / less than half the people interviewed, would also be useful.
Tell students they can add any information they like to their posters, they might have knowledge from other subjects studied at school (Geography etc.)
As a structure for the unit, you could have one lesson for introduction of the topic, study of question formation and writing questionnaires. One lesson for review of comparatives and writing up results and a third lesson for presentations.
Finally I saw on the web a site announcing a school project on European Awareness Day in Milton Keynes. I was unable to copy the link but you will probably find it with those key words. You might get some ideas from that site.