I also recommend that you try to sew with the machines. I would take thread and NEEDLE along, and some scraps of cloth like what you might use. Be sure to see if you can find helpin winding the bobbin with the thread you bring, as well as how to thread the machine and "bring up the bobbin thread" – take somebody who can sew is a fine idea.
Most home sewing machines all use the same kind of needle which may be called a 15X1 style or 735/105 or some other numbers I can not remember. They are for the same form factor of the needle (length and how gripped). There are also a number of different points on the ends of the needles for what kind of fabric the needle will penetrate. There is also a needle diameter size for fine and coarser woven fabric.
I'd take a singer 2020 (universal) needle in a 80/11 weight (one number is USA standard and the other is Metric or European standard number – for the same needle).
Bad thread and bad needles are the cause of over half of the reported sewing problems. Changing thread and needles are about the first two recommendations given for most sewing problems.
If you are learning everything by yourself, maybe borrowing a machine or renting one is the way to get over the initial hump of new learning without much risk of money.