Hi Dizzy - you are very welcome - I know we natter about nonsense, but new comers always welcome 
I honestly haven't heard about tamoxifen being used as a fertility drug, although it certainly has hormonal side effects - in my case hot flushes, sweating, general menopausal type symptoms.
Has your consultant said anything about the dosage you would be on? - it may not be the same as we are given for breast cancer and that might be a factor which alters its effects - I'm on 20mg daily.
Essentially tamoxifen is an anti oestrogen drug, - used to fight oestrogen fed breast tumours.
It also used years ago to be used as a contraceptive (though I believe not very successfully)-it's anti cancer properties were discovered when it was being used as a contraceptive.
Another side effect that I know some people on here have had (although not me as I'd had a hysterectomy) is that it stops periods.
That's all the info. I know about it - don't know whether it's helpful or not, might be worth discussing with your GP, as far as I know the way in which tamox. works is quite complicated, so it's perfectly possible that it is used for other things aside from breast cancer.
Anway - I wish you luck with ttc and hope all goes well with you 