You can take some holy water home with you. Most churches have a holy water dispenser, just bring a clean bottle of some sort. You don’t need much, a few ounces will last awhile.
Once you have it home, you may want to put it into a home font to be able to bless yourself with while making the sign of the cross. They sell fonts, but they’re not really necessary. A small, nice looking bowl will do, and if you like the more natural look, a scallop or abalone shell works great.
I put a small clean makeup sponge in the bottom of the shell I have, and saturate the sponge with the holy water.
To clean out the font/bowl/shell, take it outside and pour out any remaining water onto the ground (not inside down the sink.) Then wash as you would any other dish or bowl.