That all really depends on your height. Cutting & pressing station can be the same height -- roughly the height of your waist when you're standing. Here are the OSHA guidelines for the different heights:
https://www.osha.gov/SLTC/etools/sewing/index.html
As far as widths/lengths, I use a standard ironing board and have a card table up on blocks for my cutting station (34x34"). That would depend on the size of your cutting mat. If you are blessed with a 24x36" cutting mat, I would probably go with a cutting table that is at least 40x40" so you have a bit of room around the edges to rest your ruler, rotary cutter or any marking tools. The nice thing for me with the blocks is that I can easily turn it into a sort of Drafting Table by removing the 2 front blocks to make the front lower than the back. I can clip my paper to the table with jumbo binder clips & can comfortably work on my designs.
For my sewing table, I have an IKEA hack of their INGO table. It is 48x30" and seems like a pretty ideal size for me; smaller than that doesn't really provide enough space to support the quilt for quilting. I have my machine inset with a hole drilled out in the apron for my knee lift. If I were to do it again, I'd pick a table that didn't have an apron so I could tilt my machine because at 5'11" with an extremely long neck, it is painful for me to strain my neck to see under the top of my machine when seated in an ergonomic position. So right now I alternate between using the knee lift & angling my machine. I am planning for Christmas to get the materials to make a hanging apparatus to get the weight of the quilt up off my table for FMQ. I can't afford Quilt Suspenders, so I'm making something that is a mix of that, Caryl Bryer Fallert-Gentry's clip-on swing arm & the structure that my rolling laundry sorter uses.
Have fun designing your studio space! Be sure to post pictures when it's completed so we can all admire your hard work.
Make sure when you're planning the room you also take into consideration lighting. Plenty of bright LED ceiling lights plus some task lighting is critical. For things you don't leave plugged in all the time, like irons, having outlets at counter height is nice. I'd also make sure to include room for a design wall (even if it's just space for a portable wall). Mine is 72"H x 36"W. It's portable, but I still need to have open wall space that I can access when I want to use it.