I've had a bad experience with home plugs myself (others say otherwise), so I personally won't touch them. I've found them slow, and unreliable.
I while back, I bought 3 of these units:
They've come down in price from when I bought them - now just over £30 a pop. They are pretty awesome, and once configured correctly, I've experienced nearly no issues with them.
I run 1 as an access point in my small flat at only 10% power - this covers the entire flat. The other 2 I run in a dedicated bridge mode, also running at 10% power. All configured to wireless N, and I see about 5Mb/second when transfering files around.
I would imagine in your case, if you have thick walls, or need a further range out to the garden, just configure them at 100% power and you'll be on your way to solving your problems. But don't take my word for it, read the reviews on the DABs site - one chap there I think had the task of wifi-ing a large theatre, and these units did it cheaply, and with maximum coverage.