Were they ever planning on grouping them together as a Dominion as they did with later colonies (with limited self government), or was this something that came about as a result of the experience of the American Revolution? Or did they just have a plan to keep things as they were for the time being?
To address one of your points:
planning on grouping them together as a Dominion as they did with later colonies
The British colonies that became the modern federation of Canada were not grouped together as part of a plan by the British government.
Confederation, as the formation of the current Canadian federal constitutional order is called, was something that Canadian politicians planned, negotiated, and decided on their own. It's true that the British North America Act which enacted Confederation in 1867 was an Act of the British Parliament, but it was one written entirely^1 by Canadian politicians based on several conferences among Canadian politicians.
The prevailing attitude among British politicians in the 1860s was that the British North American colonies were getting unjustifiably expensive, since Britain continued to defend them but the colonies were internally self-governing at that point, raising and spending their own revenue and not sending any money to the British government. They thought it was inevitable that, sooner rather than later, those colonies would become independent and, although maybe they didn't think it was desirable, it was only natural that they would end up joining the United States.
The prevalent idea in the US was similar to that in Britain: obviously those British colonies would become independent since Britain didn't want to continue stationing troops to defend them, and naturally (and desirably) they would join the US since they were too unpopulous and isolated to stand by themselves.
Joining together and defending themselves and becoming more (but not completely) independent was planned and achieved by Canadian politicians, not by a pre-existing British plan.
^1 - Except for one word.
Source: Gwyn, Richard J. John A: The Man Who Made Us : the Life and Times of John A. Macdonald, Volume 1: 1815-1867. Toronto: Random House Canada, 2007.
Followup question : Did the British government have anything like Manifest Destiny, or did they have no plans of further westward expansion?
Another follow up question: Whatever plans Britain may have had for the 13 colonies, were those plans influencial in any way in shaping British plans for the Dominion of Canada?