Happy Gilmore

I have sold my own car and have 2 stock vehicles. I need to drive one to get about but how do I tax it? If I use the green slip then it will cause a cock up when I come to sell the vehicle for the new owner. I really dont want to put the car on my name and sell it within a few weeks of the car being registered in my name. Has anyone got a way around this? Any help will be appreciated. Cheers.