OK, I've had a look through most of my quilt books and I don't have all that much to do with applique so I couldn't find a pattern that was close enough to your inspiration quilt. Although I did find an absolutely gorgous tulip applique quilt, but it's not in wreaths the way the quilt you linked to is.
You would definitely do that quilt in 12 blocks, as Niecie said it would be hard to lay it all out evenly if it was one piece. Also it would be a pain to work with, you wouldn't be able to prevent such a huge piece of fabric getting all crumpled and grubby while you worked on it.
Strawberry Fayre sell plain muslin backing fabrice that you could dye to the colour you want. 90 inches would be more than wide enough for a single quilt. Cotton Patch have printed quilt back material, they're probably a bit wider than you need though. Hancocks of Paducah have a great range (the best I've ever seen) of quilting fabric including wide for backing quilts. They are in the States though so you have to allow for delivery costs and possibly to pay duty when it arrives here.
A bias tube is fabric cut on the bias so that it's a bit stretchy and can be curved easily. Basically you cut bias strips, then fold in half longways, wrong sides facing, and sew the raw edges together, giving a tube. Then you centre the seam along the tube and iron the seam open (you may need to trim the seam depending on how wide the tube is). When you applique it down you position it seam side down. Have you ordered The Quilters Ultimate Visual Guide? There is a page about it in that, but any How To guide will probably have a section on it.
I haven't been to the Ally Pally show for a few years, it is good. I found it a good place to buy my last sewing machine as I could try lots of different ones there. I've been to the Festival of Quilts in Birmingham too, it was amazing. I wanted to go this year but it's a bit of a pain as it's in the summer hols and DH is working abroad so it's hard to get away.