Welcome from a fellow CW Owner
Just make sure you don't boot it on the way home, that way when it's mapped she won't know the difference
I did this on my MK4 1.8T 6 years back, bought it and drove home steadily as my (now EX GF) came with me (we were "Saving" for a house at the time, Altho her shoe cupboard seemed to expand!), 2 days later it was "in for a service" and lo an behold it got mapped and she never knew the difference (She only drove it 3 times anyway as she was a crap driver tbh!)