Just turn up. Most CoS services start at 11am but check the board outside or the local paper fro details.
CoS is different to CoE in the way it is governed and in some of the fundamental attitudes and practices , tbh. We are a fairly conservative presbyterian church with roots in Calvinism, so no pomp and ceremony, no images to speak of, no saints or whatever, no permanent head guy. Each church pretty much governs itself, answering to a local Presbytery and operating under the auspices of the General Assembly. All very democratic in theory.
Services run, in most churches, like this:
call to worship (sometimes interactive, will be on order of service, usually)
hymn
children's address, prayer, hymn,
kids go out to Sunday School (some churches have SS before service)
prayer
hymn
reading
hymn
sermon
hymn
prayer
offering and dedication
hymn
Benediction
Amen
Doxology
Or some variation of the above, although I have been attending CoS churches all my life and I have yet to see significant variation, perhaps the offering uplifted at a different time or 5 hymns instead of 6. I like to think of it as an hour long hymn sandwich.
CoS churches have little in the way of responses and what not (minister will always indicate if they are looking for a response during prayer), no kneeling or anything like that usually (the old dears in my current church would probably die of shock if the minister asked them to kneel!) We usually stand when the Word is being carried in or out and we stand for hymns but that is usually all, unless it's a baptism or Communion and then the minister tells you when to stand anyway.
CoS churches are all individual, so there is a lot of room for different styles of worship so, depending on the minister and demographic of the congregation, you might get a traditional organist and traditional hymns (our church and most of the other churches in the town) or a praise band and contemporary worship song (the CoS that all the young folk in the town go to.)You don't have to dress up or wear a hat or anything, although some of the older ladies still do and my mother bought me "a lovely pair of leather gloves and matching bag" to wear to church for my last birthday. I am now officially old.
As AMIS says, there should be folk on the door to welcome you and give you a hymn book and order of service. If it's anything like our church, they will spot a new face at 100 yards and will be delighted to welcome you and help you out if you need it.
You don't have to join to go. Just go along and see how you get on. If you want to join after a while, ministers usually run a series of communicant's classes once or twice a year. You go to these (our last lot lasted 4 weeks, I think, mine lasted nearly 3 months back in the dark ages.) They cover basic doctrines and beliefs, a bit of church history, issues that you might want to discuss. Then there is a short ceremony where you stand up at the front and make some declarations and promises. Then you are a member. Lots of people never actually join, though, they just go along.
Joining gives you privileges and responsibilities. You promise to give of your time, talents and monies, so eventually you might be asked to take on a position on the Board, or help with the Creche, or make the tea or help fundraise or do World Mission/Christian Aid/Fairtrade/Eco Church, join the choir or any of the other things that go on.
Like AMIS, I think that you should just go along and basically copy everyone else. Don't think that you have to join in with everything or send the kids out to Sunday School if you don't want to.