Is there a way for me to protect my house from being broken? I know how locks work, but is there a way to prevent my blocks from being griefed besides living in a town?
Sadly the only way is to live within the protected borders of a town. Otherwise your buildings are in the wild and are completely free game to whomever might want to grief you.
Plots are very cheap, you could get a decent sized one for only $1000. Ask in trade chat and maybe you can find cheaper if someone has a builder town
Try living in a less-populated town with higher-ranked players. In protected towns, the only players that can grief your home would be the other town members while in the wild, everyone on the server can grief you.
Many people who live in my town are mayors. I provide high quality living, however I don't sell plots and prebuilts are at least $7000. If he is fine with an apartment, he will be very safe in my community