Colin,

I am afraid you can't do automatic failover using Log shipping and this has been one of the big drawbacks of LS. In LS the primary and secondary server will NOT be in sync normally and you may want to bring them in sync first by making sure the tail of the log backup is taken on the primary and restored on the secondary. Otherwise depending on the restore delay on the secondary there is a chance for significant data loss.

Failing Over to a Log Shipping Secondary

http://blogs.technet.com/b/josebda/archive/2009/04/02/sql-server-2008-log-shipping.aspx

If this answer is NOT helpful then please add more details about the condition of primary, sql server version, if data loss is ok on the secondary etc...

Thanks,

Sankar Reddy

Yes, Log Shipping doesn't provide option for automatic failover - you may use Database Mirroring for that.  There are few steps you need to follow while performing role switching

1. See if the primary server allows you to take a tail-log backup and apply it to the secondary server with recovery option

2. Ensure that you have all the logins transferred and are synch (actually this should have set up the time you've configured Log Shipping) 

3. Ensure that you have all jobs and DTS package transferred to the secondary server, you can achive this either scripting on primary server and executing them on secondary server or using DTS package 

4. Point you application to the new server by changing the connection string...or what ever method you used to connect to your database server

Here is a link of white paper for Log Shipping for more reference - http://download.microsoft.com/download/SQLSVR2000/Utility/2.0/WIN98/EN-US/log_shipping.exe

hope this helps..

Regards

Hemantgiri S. Goswami | SQL Server Citation