So I've had interest in this girl at my work for about 4 months. I didn't go for it till now as I was interested in her for more than just sex and she's just split from her ex of 3 years so I didn't want to either step in his grave or just be a quickie.

Anyway got with her a couple nights ago and all the classic signs of big ioi in the morning. Telling me how amazing my eyes look, staring into them, not being able to leave my house, all the usual jazz. However she's shooting off to france for a couple months on Sunday. I'm seeing her Saturday night. I do actually like this girl so the 2 months will be frustrating but it has to be done.

I'm assuming I should go for a more relaxed approach till she's back i.e. indicate that whilst we obviously do like each other its understandable that its just "begun" and we should "reboot" the situation when she returns and that both of us should just have fun whilst she's away.

If you say nothing that's probably implied, no? I mean you're not dating the girl.

You could ask her for contact details while she's over there and tell her you'd like to keep in touch while she's having a great time.