Just rung them and turns out it's best I did, as the first appointment they had was the 28th, and if I'm still pregnant by then I'll be nearly 11 weeks, so I guess it could be a tight turnaround for the dating scan... So I think good I didn't leave it another week, so thanks for persuading me life!
Baby dreaming sorry you're feeling worried too. I know you're right that stressing won't change it, but it's so hard not to! I thought I'd feel a bit better once I was past the point where all three failed before, but I'm really not. I think I've just fundamentally lost faith in my body - it feels like there's no evidence it can do this, and so much evidence it can't. I know there's no point thinking like that, though.