You only have limited time at work to learn Perl, but this needn't stop you learning it in your spare time.

What things interest you? If you're a wine enthusiast, you could use Perl to create a database of your cellar contents, with a web-based interface allowing you to rate the wines you've tried.

Or if you're interested in Sci-Fi, you could write an interactive Sci-Fi novel using Perl. (Like the Choose Your Own Adventure books, but with the added advantage of being able to store state.)

Or maybe you're an amateur photographer, in which case you could try writing your own Flickr imitation.

Come up with some kind of idea, and implement it. Write it as an open source project, so that other people can use it. You can learn from people's feedback, and from any patches they contribute back to you.

Programming is not something you can learn entirely from reading. It's something you have to learn by doing.