You may be assuming the worst when something much less can be the culprit.. Have you first looked to see if you can tell where the anti-freeze is coming from? Have you checked all the hose clamps for tightness/integrity? Could there be a small crack in the overflow hose to the bottle?
If nothing else, have the local garage do a pressure test. That alone might be quite revealing.. I'm hoping you won't have to spend a ton of money for water pump or a radiator...
Best to you.
