dp wrote:
If I feel under the
bath I can put my hand right through to the inside of the outer brick
wall.


I'd just brick that up with some more blocks.

So basically some of the
breeze block wall is resting on a waste pipe, albeit around the pipe
it has been cemented up. I know this sounds pointless but thats what
the pipe does!

I wouldn't think the pipe is holding up the wall, it's probably just been
cemented to make good.

3. Is it advisable to try and move the waste pipe or is it best just
to leave it as it is?

If it's not in the way leave it. If it is, move it.

Dave