Thanks everyone for being lovely - I was worried I would bore everyone with my back story!
I had a thread on MN about it (different name) when I was deciding what to do. I had a huge amount of support, but also a lot of people telling me that I can't persuade him to have DCs if he doesn't want to.
So I was really careful not to try and force him. There was no ultimatum, I just came to the end of the line and knew that if he never agreed to it, it would eat away at our relationship and kill it in the end anyway. Which was so sad, because we had waited so long to find each other, and were (and are) just so happy together. As soon as I left he had the space to think and came to his senses. So we booked the reversal op, and booked a fabulous diving holiday beforehand thinking it would be our final 'adventurous holiday' before DCs... that was almost a year ago.
He has been brilliant since, he's a pretty determined man so when he decides to do something he sticks to it.
Min I understood exactly what you meant about him not seeing the crazy
he'll never know how many pee sticks I've got through...
It's the reason why I've managed to get the FSH and Day 21 tests done early - my GP was lovely about the whole thing and said that we should test me to make sure I was in working order before DP went through with the op. Unfortunately, with my progesterone levels still seeming low, it seems there's something amiss but we'll see.
It's also the reason why I'm a bit highly strung about the whole thing - we've been through a lot to be able to JS to ttc like normal people, you know? I had already convinced myself we'd be infertile or sub-fertile at best, but we're apparently normal!
And it's also why I'll never manage to be chilled and relaxed about the whole thing... we've already spent £3k on ttc, I want my money's worth 
Blargh, anyway that's enough about me.
You naughty lot, you're really selling the idea of OPKs to me now!!! tell me more