Welcome to the HW forum this is a great place to come and meet people who can relate to what you are going through. Sorry to hear you are having sleep problems at the moment, I have bad insomnia and find that lack of sleep makes my gad/depression a lot worse. It is really important to have a sleep routine which you do every night to relax and ease the racing thoughts, As others have mentioned reading is a good way to help make you feel tired but you must not read in bed as your body gets used to going to bed and then not going stright to sleep, so I would recommend you have a comfy chair in your room were you could read or listen to music which I find helps me most as not a big fan of reading. Also if you wake up then get up out of bed and only go back to bed when tired im sure these will be some of the things you will find out when you have your sleep study.
I would maybe go and speak with your doctor and see if they can give you any thing to help you get some sleep until you have your sleep study. Have you ever had any therapy to help with your anxiety and depression? CBT is a type of talk therapy which has great results with people who are suffering with anxiety and depression, I am due to have some soon and I know a lot of members here have had very positive experience with this kind of therapy so might be something you could look into?. Please do keep posting and tell us how you are getting on you are family now and we all support each other.