Could a lapsed Catholic return to the Eucharist simply by confession? Or are there other impediments that keep them from ‘legally’ communing?
Can. 912 Any baptized person not prohibited by law can and must be admitted to holy communion.
Can. 916 A person who is conscious of grave sin is not to…receive the body of the Lord without previous sacramental confession…
If there are no other outstanding issues (e.g. married outside the church) then a lapsed Catholic would only need to make a good confession in order to be able to receive communion.