On Tue, 13 Apr 2004 07:51:24 +0100, in uk.d-i-y "Graeme" strung together this:
You can get a surprisingly good fixing in a strawmit wall by sticking a 2"x10 woodscrew straight into the wall, try it.
It's entirely up to you which way you do it. If it were me I'd fit the bath then tile up to it, it's always worked for me.