Thanks for the messages, peeps!
And congrats to KLou and keeping fingers firmly crossed for SQR.
Mrsden, tbh it's a difficult one to say much useful about how I knew. I am a total control freak, and since I got pg on 1st cycle last time (and am a teacher so want a baby at a certain time of the year!) I was fully expecing it to be positive first time round. I'm one of those people who 'knew' 
- though I'm aware that many people 'know' and are wrong :(
Having said that, I did think I felt some moving and stretching in my groin muscle area - I've heard second time around it all happens quicker, and I suppose I know what to listen out for.
Though no really strong symptoms until 4am the day I was actually due on (Thurs). And now I feel like complete cack and have done ever since Thurs morning.
I tested because I felt crampy, dizzy, nauseous and sobbed when Jack Duckworth's death scene was shown on This Morning.
In terms of getting the SWI right, I think we were lucky - I knew when to do it but am rapidly coming to the conclusion that DH only has to look at me if it's the right time and I'm upduffed 
.
Good luck to everyone still to test.