A clinic may ask for a blood count, blood group and Rh, fasting sugar or HbA1c, thyroid, and screens for infections such as hepatitis B, hepatitis C, HIV and syphilis. Folate status matters because supplements are often started before conception. Some couples add rubella immunity, which is a separate test you can request on a prescription.
For women with irregular cycles, FSH, LH, prolactin and AMH are common. For men, a semen analysis is a lab visit, and hormones are added if that result or the history suggests it.
None of this is a fertility clearance. It is a folder you take to the appointment so the visit is about decisions, not about waiting on basic labs.
This article explains how tests are used. It is not a personal diagnosis.