Need some help/advice.

Not to sure if I'm in the right group.

Me and partner have been ttc for 3 years, we have a 6 year old daughter who took 1year and half to conceive,

Recently been dmto doctors and they are referring us to the fertility clinic after I've done 3 sets of bloods and smear (all done) and my partner has to do a sperm sample which he doing tommorow, today is cd1 😭 really thought we were in for a good chance this month using preseed but obviously not 😔 when I get the letter through for our first appointment what should we expect from first meeting? What questions do I need to ask? How does the process work? So nervous but so excited at same time, didn't want to go down this route but unfortunately conceiving by ourselves is becoming near impossible. With our daughter growing up fast she everyday asks for a brother or sister which rips me heart out knowing is not that easy.. Just wish to hold a bundle of joy again 😍 hope you can help.