Abnormal smear- colposcopy!

Hi, I had a smear test 3 weeks ago before I found out I was pregnant, I have just recieved a letter saying I have to go for a colposcopy tomorrow!! I have had no phone call or any other communication other that this letter saying I have to go to hospital? I am now 5 weeks pregnant and I have no idea what this means?! I called NHS direct and they have just told me I have to wait until tomorrow to call and ask what to do? Has anyone had this before? I am already worried about my baby miscarrying and now worried about myself too!