For your first quilt stick with something that's only squares and rectangles.  As soon as you start cutting on the bias things can start to stretch out, no matter how experienced you are with other areas of sewing it's still more difficult.

The first pattern you showed had blocks made of squares, but then they are rotated 90 degrees (on-point in darkside speak) which means that there has to be setting triangles around the edges and they are not easy to deal with!.  The other pattern looks good, and as others have suggested disappearing 9-patch, or one of the many variations of rail fence.

The secret to getting a good looking quilt is to get the right balance of lights, mediums and darks.  Look at that second pattern,  The sashing (the strips between the blocks)  is light with dark corner stones (the small squares where the sashing strips cross) are dark.  The nine-square patches are mostly medium values with a few darks, but the middle one is always light.  If you make each block with a different mix of colours it will look more interesting, and no possibility of getting a block "wrong" or running out of one of the fabrics for the blocks.

Your selection of fabrics looks good, especially for that pattern though you will probably need to buy yardage (meterage?) of the light/white for the sashing.

My rule of thumb to how much fabric is needed for a quilt top is to work out the total area of the quilt top and double it.
That takes care of the seam allowances and the inevitable wastage of a few tiny scraps.

Excellent advice from @Renegade Sewist

Nothing to tempt me either.

@JenHampson to do an alterations business you do need some business savvy but mostly you need to be a competent and confident sewist. Generally your client knows exactly what they want, can't do it themselves and expects you to be a genius at figuring it out.

If you're not competent no one will be satisfied with the work. If you're not also confident in your abilities and experienced you won't be able to know how much time various things take to complete or what you need to charge to make it worthwhile.

You don't need any accreditation to do alterations. You need experience. I would start by altering everything my family owned that could possibly need any alterations. Take buttons off shirts and put them back on. Better yet, remove half of them then put those back on so they properly match the others. Take a perfectly good zipper out of a skirt or pants and then reinsert it. Shorten a pair of pants half a centimeter.

Maybe do some work for friends for experience. Then visualize doing that for eight hours a day. How many days a week would you enjoy doing it?

BTW from what I know from friends is that if you're working for private clients they are always in a rush.

I like to work with hsts. Windmills would look good