43mm waste pipe...where can I get some?

I need to replace a 43mm waste pipe that runs from under the bath plug hole, out of the wall to the outside where it meets an elbow section and a straight bit of pipe that runs into the drain.

However I've visited the visuals sheds to find they only stock 40mm waste pipe now. Is there anywhere I can get 43mm pipe and elbow, or is there a 43mm to 40mm reducer part that will help here?

Thanks

Did you measure the outside diameter and is it solvent weld?

43mm is the normal OD for 40mm SW pipe

If you are unsure if it's solvent or Pushfit you can always use a mechanical coupling (MacAlpine or similar)