If you're expecting a step-by-step guide about how to fix a broken chain, I'd wait a few more days till I'm actually able to do that. In the meantime, here's some "DON'T"s that may prove useful
1. Don't turn you bike upside down without removing your (open) panniers firstPicture says it all really
2. Don't forget to make a drawing of where the chain goes firstYou'll forget as soon as your trying to re-attach the chain and when you're covered in oil is not the time to be looking round your house for a picture of a bike.
3. Don't re-attach the chain (using the SRAM link you bought) in such a way part of it is running outside of the frame.
You'll just swear a lot
4. Don't think "That's OK" - it should be possible to just slide my SRAM link back apart againApparently it *is* possible, but it requires skill and pliers, and not oily hands and no skill.
4. Don't think "That's not a problem", I can use my bike chain tool to remove another link, move the chain back inside the frame, before re-attaching the link using your bike chain tool. 
The bike chain tool should be used to push a pin out part (but not all) of the way. See
here for how to do it properly. If you do push the pin all the way out, there's no way on God's Green earth that you'll be able to get it back in.
I will now be buying another connex link, to replace the link where I took the completely out and hopefully I'll be able to be back on my bike (finally)