The 1998 data protection act is about data relating to you - the data of your friends would not be covered (obviously it would be covered for them).
Even for that data, while the (British) law states that people must be able to claim the information stored about them, they have to submit a request, and the company is allowed to charge a small fee.
Stored lists of related individuals are covered by the DPA 1998, just not their personal details other than their name. This is not explicit but implied by the fact that related people on a credit file can be obtained under the DPA setting a precedent for access.
This has been demonstrated a few times in court but I can't be bothered to dig around for references.
Even for that data, while the (British) law states that people must be able to claim the information stored about them, they have to submit a request, and the company is allowed to charge a small fee.
So, no, the data protection act isn't relevant.