When the midwife does our ultrasound and gives you an age of 7- 8 weeks is this including the dates of you lmp?? Or exactly how old the baby is

No, ultrasound is used to determine how developed baby is. This can often alter the due date, which is usually first given as 40 weeks from the first day of the last menstrual cycle. That most women are not actually pregnant at that time is why ultrasounds can change due dates a bit. Keep in mind, however, that ultrasounds do not date exactly either; they go by averages. You will still have a window of about 4 weeks at the end of your pregnancy that would be considered a normal time for giving birth.

Please do not start a new thread that really relates to your other post. As noted before, the scan will not tell you at this point which man is the babies father, you will have to wait till the child is born for a DNA test.