Awesome dude,thanka ya much,
Your welcome.
I take it the foam I`m lookin for is about 100mm thick
Yes, Well, however these panels can(and should be) made of fabric wrapped RIGID FIBERGLASS such as Owens Corning 703, or equivilent. The thickness is actually 4" for those who aren't familear with metric dimensions. I know rigid fiberglass is probably very difficult to find in Scotland, especially 100mm thick. But you COULD build wood frames and stuff them with 100mm 3lb density ROCKWOOL or equivilent. I highly doubt you could find 2'x4' panels of the CORRECT foam and density, especially in Scotland, but I may be wrong. If you could, this would be the simplest to impliment, as all you would have to do is cut it. However, the rigid fiberglass and mineral wool type products work better.
There are many ways to do this stuff. It all depends on your construction skills, tools, material availability, and most of all... imagination. The angled corner diagonals would be the most difficult to impliment, simply because of the intersecting angles...at least to make it look appealing and work correctly. If placing them diagonally across these angled corners is too difficult for you, you could place them flat against the wall, but it won't work as well for bass trapping.
I can draw up a set of alternative construction ideas for ROCKWOOL type framing as Rockwool etc is difficult to simply wrap with fabric, as it is a limp mass product and isn't rigid like the fiberglass products. Again though, I'd have to know your skill/tool level to design them. I am very adept at construction as I've been a journeyman millworker/cabinet maker for 30 yrs, so this stuff is easy for me. But I have a shop too, which makes things like this easy to build as well as design. Remember too, there are hanging issues, and backing issues and fabric wrapping issues, that all have to be thought out in advance to make this stuff come out the way I envision it. I really don't have time at the moment to go into all the little details that must be addressed when building these sort of things. And the designs actually depend on what sort of ABSORPTION materials you have abailable and can afford. So let me know what you can get there and we;ll work from there.
The curved panel on the back wall,is that something I can construct myself,like outta finished ply? if so would it need filled with anything?
Yes and yes.
The simplist way to make these is to fasten two cleats as show(there are other ways as well, which I'll show later)with wall anchors and then insert one edge of 1/4" ply sheet under the lip of one anchor and bend it till you can insert the other edge under the lip of the opposite cleat. Then stuff regular batt insulation into the void, although there is an alternative to make it easier, but more expensive. I'll show that later as well. You want to center this on the rear wall. Also the width dimension between the cleats is important to get the right curve(not a perfect circle, its actually an elipse) with a panel thats 48"wide(I made this 72" long btw)
Sorry dude,zero knowledge of this stuff.
Well, isn't that why you came here?
Voila! Answers.
BTW, the array of square absorption panels on the rear wall are intentional because of this known fact. If you have say a 4'x8' panel of absorption material on a wall, it will absorb X Sabins of sound( ONE Sabin of absorption is equal to the absorption of a 12"x12" OPEN WINDOW). However, if you cut this panel into, say, 12"x12" patches, and arrange them in a patchwork array, the will absorb as a WHOLE, more than the panel in one piece. This is because of a known phenomena called the EDGE EFFECT, whereby DIFFRACTION at the edges contribute to the absorption of the patchwork as a whole. Not only that, but because of the areas of absorption having a flat wall boundary in between, another phenomena takes place called "impedence difference"(simple explanation) whereby reflection and absorption take place...which in effect allows DIFFUSION somewhat to occur. Don't ask me for details...this is a much simplified explanation...suffice to say, thats the reason for the patchwork design. The poly helps "scatter" the sound, which is not really diffusion...but it is a simple way to reflect sound at angles from a close proximity rear wall. However, this only helps with mid and high frequencies. Low frequencies in a SMALL room are a bitch to absorb. Hence the use of panels applied diagonally across the corners as Low frequency modes terminate and reflect out of the corner intersections. ALL OF THEM.
What I had NOT shown YET, is diagonal panels applied across the rear wall/ceiling intersections and the side wall/ceiling intersections. I didn't have time for that and still don't. In fact, I have to leave now. But I'll be back.
fitZ
btw, heres a picture of one of the frames I made for fabric covering my sidewall/ceiling "superchunk" absorbers, and a jpg of how they look in sketchup and a jpg of a model of my control room absorption scheme jsut to give you an idea of what you can do if you have the skills, tools, and imagination.
will pop in here for ya but I think if it were my room, I'd start with the computer at the wall with the window (kinda like where it is now 
