"I know that at St Mary's Cathedral in Glasgow (the Episcopalian one, the "English Kirk") invites everyone to join in communion, come what may, no questions asked. At the big medieval church at the top of the High Street commonly called "the cathedral" although it isn't one, there are communion services but I'm not sure what the rules are: having being confirmed by a bishop can't be one of them because, as Flanders and Swann once pointed out, we don't have bishops to show us the way. Not in our established church anyway.
But in any case it should be between you and God whether you are qualified to commune with Her, not a matter of having a piece of paper. If somebody is not enough of a believer to want to attend the service and partake of the eucharist then why would they? It's hardly sticking it to The Man."
You're right, LadyHonoriaDedlock, that the Church of Scotland doesn't have bishops. C of S churches which have been cathedrals in pre-Reformation days still keep the name - Glasgow, Dunblane, St Machar's, etc. We don't have confirmation in the same way as the Roman Catholic Church or the Anglican churches, but you can choose to join the church in your teens or at any time as an adult. You then take vows about joining in worship and committing time, talents and money to the church as appropriate, as well as expressing your faith. Anyone who loves the Lord can take communion, whether a member of the C of S or any other church, or not at all, so it's a personal decision. I'm sure God can cope!
Just for information, the Church of Scotland is not an established church as the C of E is in England. We have no established church here. 