Hi Chris,
I was about to point you in the direction of a great program written by thomas which saved all of my data under similar circumstances
http://aminet.net/search?query=rdbrecovBut unfortunately it says this in the readme file:-
Use RDBrecov if you lost the RDB (partitioning information) of your
harddisk.
RDBrecov searches an entire harddisk for partitions. It can handle PFS2,
PFS3, AFS and SFS partitions.
D'oh!