When flushing the toilet the water seems to gurgle and sometimes spits up out of the bath and shower plug holes, it also flushes away slowly, this seems to be worse just after emptying the bath water. Any ideas how this can be solved ?
2nd: Your pipes are backing up somewhere, check under the inspection cover on your garden if you have one. You can have it rodded out if its down there.
You could also try something like Mr Muscle Sink and pipes unblocker, which might do the trick
This could also be caused by poor plumbing in the sense of a poorly planned/executed installation.
We have the same (to a smaller degree) interaction between bath & washbasin. Emptying one will cause the other to gurgle and spit. Ours is caused due to the layout we wanted, the outlets are combined into one pipe and the combined wastepipe doesn't have quite enough fall on it to drain rapidly in the right direction.
Both of the above could be right - the key is in whether it has always done it, or whether it has started doing it and gradually got worse. If the former then Catso is probably right in that it is poorly designed pipe layout. If the latter, the pipes have gradually and partially blocked up - as per Theren.