How do you find out due date if you aren't sure on dates?

[pumpkin2]

I have just found out I'm pregnant with no. 2 - but cannot for the life of me remember when my last period was! DH is amazed that I don't record these things - but tbh I haven't ever really bothered, especially since we were relaxed about the possibility of a second pregnancy - if it happens, it happens, sort of thing....
So, my question is, what can be done for disorganised women like me to date the baby? Do they give you some sort of scan or sthg to establish how far along you are?
thanks!

yes, they always give you dates from scans. I wasn't sure about my dates, but the one I've been given from my scan is definitely not when AF arrived anyway!

I was given my due date from my scan and they are pretty accurate. It is all based on various measurments, the circumference of the head being oneof them I think.

yes, the 12 ish week scan will do that. it's one of the functions of it.

thanks all, will look forward to the scan then to find out (approximately!) when we're due!