Hello there, I started a very demanding job two months ago and tomorrow someone in the team decided to host a bbq, and it would reflect badly kn me if I were to miss it. Because I haven't received my car yet and where I live there's no bus available at the time of the bbq, a colleague insisted on picking me up. I accepted her kind offer 
; however, I'm worried that when she picks and/or drops me off, she'll want to come into my house with the excuse of  having to use the bathroom. Currently, my house is a true mess: I have been working 10 hours a day and my free time I dedicate it to walking my dogs, so there's very little time for cleaning and I can't do so for tomorrow. So my question is : in case my colleague ask to use the toilette in my house, what would be a polite way to keep her from using it?

To give a little context of the workplace, it is quite toxic - like House of Cards level of toxicity:  People are very cunning there and they usually try to do everything in order to mannipulate the boss to their advantage, and often that includes bringing a few colleagues down. Unfortunately, I have absolutely no idea on how to "play the game" so I often keep to myself and socialize very little, which is why I'm sure my colleague might want to enter into my house so as to "evaluate me".

Please, don't be too harsh on me on the fact that my house isn't clean, Im trying my best. If I could I would not go to the bbq or even just clean it all. I really need help on this one.