You do not have any particular design of logbook and there is no longer any such thing as a "JAA approved logbook". The various 'JAR-FCL logbooks available are copies of the design that used to be contained in JAR-FCL 1.080 and, being in Section 1, was mandatory. Now, however, this has been moved to IEM FCL 1.080 in Section 2, which is Interpretive and Explanatory Material and shows an example only of how a logbook might look.
The UK law relating to the maintainance of a personal flying logbook is spelt out in the ANO at Article 28 and says nothing about the design of such a logbook. Provided that you comply with this law, you do not have to do anything else. It is perfecly legal, for example, to maintain a personal flying log on a computer or PDA if you wish - you are not obliged to have a 'book' at all.
The way that you choose to comply with the law is entirely up to you - you may use whatever design of logbook suits you and the flying that you are doing.