A quick note on doors..... I built my own for buttons
I bought some 4"x2" timber, and a couple of sheets of 8'x4' ¼" plywood, some 8x4 plasterboard and 4 2" right angle brackets.
I cut the 4x2 timber down to 3x2 on a table saw, 2 sides a top and bottom.
1.Use the angle brackets on the insides of the corners of your door frame on the 3" side of the wood
2 nail a sheet of ply over one side of the frame and flip the whole thing over
3. cut 2 sheets of plasterboard (this should be the 12.5mm stuff I should mention), green glue one sheet of plasterboard inside the frame and onto the plywood.
4. drop in some 2" RW45. If you cut the frame down to 3" you should have 12.5mm left to drop in your other sheet of cut plasterboard
5. green glue it and cover with the other sheet of plywood and nail it all around the frame.
6. stand back and admire your super new door

Don't worry that it has no handles or latch mechanism...the handles that go right through the doors with a bar that works the latch need a big hole that you can never seal properly. Instead get a fixed screw on handle for the side that pulls, you don't need a handle to push a door open on the other side.
Get one of them little screw on sprung ball latches from B&Q for a couple of quid....buy a cheap small chisel with the change from your fiver to mortice out the recess in the door for the sprung ball mechanism to sit in and to take a bit out the frame for the same purpose when the door is closed.
Now a door is a door but it's the seal and the frame that make a door a good studio door. Best thing you can do is MAKE the doorframe to fit the door you just made, it's easy. This time use 6"x2"...think I used 5"x2 if I remember correctly cut from 6x2 on the table saw. Lay the door down and build a 4 sided frame around it using 2" thick for the top and sides and 1" for the bottom...yeah everyone forgets and trips over it but it lets you put a good seal all the way around the door. Don't use that sticky backed foam stuff on a roll for the seal. You want the good hollow circular rubber stuff........you're thinking that's gonna cost more than the door, right? Wrong....get up your local car scrap yard with a stanley knife and help yourself to some door seals...volvo ones are good if you can get them