Ok, switching from outdoorsy wholesome type to computer nerd...
Buy Avery labels, use Microsoft Word, choose Print - Envelopes & Labels, select the exact type of label that you have bought from the list and it will work, every time, promise. (Use Print Preview before printing to check it looks ok and no print is too near the edges of labels.)
Alternatively, find a local teenager to do it for you, or maybe [someone at] your local library can help if they have PCs.
You can also use the computer label sheets in photocopiers, so if nothing changes or the only thing that changes is a date / batch number and you could write that on by hand, you could get someone to set you up a template / master copy and then just copy it.
Best of luck!