Listen carefully. Most girls will react badly to a neg and I rarely do it unless they think too much of themselves and they have an ego problem.
Save it for the HB9's I always say to myself but I do not know any.
They all have 2 tits and a pussy and most bore the shit out of me after a very short time so I tend to score them down.
I tease a lot but not neg.
You family is not the problem. Your parents know about the 'birds and the bees'.
They had sex to have you.
The issue is how you are perceiving their reaction when there most likely will not be much of one if at all. You are an adult I assume in your 20's.
I used to just tell mine that I was staying with a friend or friends. No real questions were asked but I would have said yes it is girl who is a friend of mine.
Have no worries. Set the date and get a decent BJ and fuck her hard.
I had a lot of English girls when I lived there (South East) and know their mentality well so hit me up with a PM if you want anytime.