Help!

So my period is now 5 days late and I need to sneak away tomorrow to buy a pregnancy test but I have no idea what to say about where I’m going! Me and fiancé are quarantined together and any time I leave the house he’s so excited to come with me (he’s not a home body at all and hates quarantine). Idk where I should say I’m going that he can’t come with me?😭 I don’t want him to know I’m buying a pregnancy test because if I’m pregnant I want to surprise him. We have been ttc but he has no idea I’m late! Idk what to do but I need to test, my curiosity is eating me alive!