In my experience (~ 18 years ago, so things may have changed), Home Depot does a good job of providing a design, including cabinets, appliance location, etc. However, they normally work in the store based on information you provide them. Garbage in, garbage out - they can only work with what you tell them. That was good enough for me as I improvised as I went along and I had an electrician and plumber who were both flexible and able to improvise too. Of course, in my case I knew the cabinets between kitchen and dining were non-structural, and I also had full access to the electric panel, gas & water lines all conveniently in an unfinished laundry room directly beneath the kitchen - most people don't have it so easy.
Many of the Home Depot people are semi-retired people who used to work all day in construction, renovation or specialty trades for a living. I'd suggest looking for someone of that sort who is willing to go to your house, for a fee, and evaluate a bunch of the key issues on site, where they poke into things and get a good idea of structural, electrical and plumbing issues that might affect your project. This might be a small contractor, as suggested in another answer, or might be an individual who is no longer active in the business but who has experience built up over many years.
What you want to avoid is giving anyone the impression that you are trying to get a free estimate based on them possibly getting the job as general contractor. Nothing gets people more upset than being tricked like that. But if you are up front, and willing to pay a reasonable consulting fee, you should be able to find someone to help. Try networking through your local church/synagogue/school/neighborhood/etc. email group, friends & neighbors, etc. and it shouldn't be hard to find some experienced tradesmen (or women) willing to earn a small consulting fee. They can also help advise on any permitting issues (much more of an issue in some areas than others) that might affect the planning of your project.
For the "Home Depot, etc." part of the design, no fee is normally involved but there is an expectation that you will buy at least some of the items from that store (in my case, I got all the cabinets, sinks, exhaust fan, flooring from Home Depot but went elsewhere for appliances to get the items that Home Depot either didn't stock or didn't have at the right price).
As far as doing "most, if not all" of the work yourself: A lot varies by area. In many places electrical and plumbing need to be done by licensed electricians and plumbers. Even if that is not the case, I highly recommend using a professional for anything you're not comfortable with. In my case, that was electrical (I've learned a lot since then, but some parts of it I still wouldn't do myself) and plumbing (both gas and water). If you have some experience you may be able to do much of those items yourself. But I urge caution on gas (if that is part of your kitchen plans) as a mistake with gas can have extreme consequences and problems can be much harder to discover (and stay safe) than with electrical and water.