Are you allowed to play Blackjack on your own with one hand?
A lot depends on how the house perceives you as a customer. If you are a "regular" and have played many rounds with them in the past, they will likely deal to you alone today, even if you only play one hand.

If this is your first time, and you've been betting the minimum, that's kind of a different story. The house may then decide that it's not worth the dealer's time and effort, and may require a "two hand minimum" to run the table, either from you, or between you and another party.