Hello Oli,
You don't have to register to do the camino. If you are from England I would recommend that you join the Confraternity of St James (London) where you will find all the info you need on routes, how to get there, what to take etc. Members are also able to purchase a 'credential' or pilgrim's passport which is necessary to stay in the refuges along the way. We are not sure yet of the new rules regarding the issue of credentials by other countries and this might change. There has been talk of only official, Spanish credentials being accepted from 2008 at refuges and at the pilgrim's office for the awarding of the certificate of completion, the Compostela.
http://www.csj.org.uk
The DVD "Welcome" states that the authorities are expecting up to 5 million (!!!) pilgrims to walk the different routes in Spain in the next Holy Year - 2010. The movie shows the type of accommodation that might be used to house pilgrims, including an award winning metal container-cum-albergue.
I think it will be very exciting to walk the camino in the Holy Year. I walked it in 2004 and the vibe was amazing! The next Holy Year will be in 2021 - some of us here might be a bit long in the tooth by then but I am aiming to walk it again then!!
Good luck with your planning,