Alrite mate, love the use of the word banter there- i love banter
I'm pretty new to the game in general but from my past experiences I'd say that you should go with honesty in this situation. Don't make a huge joke out of it, like with the virginity police thing- or maybe make that joke and then say something along the lines of "I haven't found the right girl, that I want to lose it to". But don't make out that you haven't done anything with a girl, make it out as though you've done the 'lesser' sexual activities but through your own choice you haven't gone the full mile. < This is what I did before I lost my V-plates. It doesn't make you seem like a desperate virgin trying to lose it, rather it makes it seem like you're a respectable lad who hasn't made that decision yet.
BUT, it depends on age. I was 16-17 when I was using the "haven't found the right girl" excuse, the people that I told this to were also around the same age. It will most likely be different if you're older, you say you're 3 years older than the girl and I'm assuming the girl's atleast 16 so you being 19 I think you'd still be able to get away with the above.
At the end of the day though, it's your choice. Feel free to disregard what I say and do what YOU feel is right. Just don't go having sex with underage girls