The parliament of our country is our embodiment as a people of our collective will. Therefore, we should not give that will up to others, except on a temporary, mutual basis. We should not be able to bind our successors and descendants.
All international treaties in some way limit the power of our own government.
Some treaties, however, limit the legislative freedom of the UK. Such treaties should not be allowed to be permanent or irreversible. (For instance, wording such as "an ever closer union" should not be permitted in a treaty).
Any treaty binding parliament's legislative sovereignty should be subject to ratification and re-ratification in a referendum. In other words, parliament must ask permission to temporarily cede its sovereignty.
Such referenda should happen at least once per parliament, since no parliament should be able to bind a subsequent parliament.