Like YamaB said, I am shocked that the track doesn't have open practice days.
The tracks near my house have race days where there is a little practice time before the races start. Race day is usually on the weekend. But then there are a couple of days during the week that the track is open to the public. Costs $25 to ride but all it takes is to pay the cash.
I would recommend finding a track that you could practice on before race day as it might be quite an eye opener for you. Out here in California we have a lot of state owned off road recreation areas and many of these will include a "MX track". The tracks are generally pretty wide open, will have a few short table tops and maybe a double. They may water the track once a day and the conditions are usually pretty hard pack.
Then there are the private tracks. These tracks compress the same distance into 1/8th the area, which means if you lose control and blow off the course end up on a different section of the course, probably going the wrong way. they water the heck out of the course, which makes it soft which results in deep ruts in fairly short order. And the jumps are bigger. Way bigger. At the state park the double jumps are something that you could roll no problem. At the private track the doubles are something that you really want to clear.......
For example, at the Santa Clara MX track the main table top (in front of the bleachers) is at least 50 feet across. Rolling it is no problem at all. Landing 20 feet in is okay. Landing at 50 feet, on the down slope, is sweet! Landing at 49 feet is a bitch.
There is a double that I have never managed to clear, and attempting to jump it generally results in a crash. There is another double that is so sweet IF I am wound up in third gear going up the face. If the rut in the corner has me off balance, however, I'll hit the brakes and roll it as it can really hurt to land a few feet short on a double. They change the course up about once a month and it takes me a few slow laps around to figure out what jumps I can attack and which ones I have to be careful on.
The track can be a blast and I encourage you to enter a race, I just suggest that you might be a lot happier if you could get the hang of the doubles before race day.
Oh, and have you tried any rhythm sections yet??
Rod