Damn! But I can't really afford £120 either, so...
A few tips.
1. Do NOT compare yourself to anyone else on the race track for your first meeting. You will be slow, and you will feel out of your depth. The ARDS test and track days are NOT preparation to a competition environment.
2. Take your time. Most club races are about 15 minutes per session. You have to do three laps to be allowed to race, and your times don't matter. Use the time wisely - take a few laps to bed brakes and tyres in. Spend a further couple of laps getting basic markers for braking and turning, and LOOK at the track surface for cambers, irregularities and kerbs. Only then think about going a bit quicker.
3. Take all the advice you can - ALL of it is worthwhile listening to and digesting. But don't take everything at face value - some of the advice will help, but for the wrong reasons - the giver might not even know why something works, and knowing why is way more helpful than just knowing.
4. Stick to your lines, and don't do sudden stuff - if people are behind you in practice they will find a way passed. If they are behind you in a race then don't think about racing too much yet. If you are having to pass slower cars (in a lower class), whilst being passed, then you'll have a lot more pressure, but the big yellow novice cross is to help people behind - people ARE considerate.
5. You will learn far more in 15 minutes than any great setup tweak, so do not adjust the car at all (unless it is really dangerous not to!). That way you will have the same car in the car that you did in practice, and you can continue learning the car/track, rather than a new variable change. Setup changes are something to save in the future when you've got a bit more experience (at least two races really, but it does depend how much track driving you've done).
6. Enjoy it. It's expensive. It's time consuming. None on the grid are good drivers (otherwise they wouldn't be in club racing!), and the whole point of going club racing is to enjoy yourself, experience some thrills and have something to chat about in the pub - so make sure you come away with a smile. You will have a much bigger smile having lost a place on the last lap through inexperience than you will with a heavily damaged car, a cross rival driver shouting at you, and the cost/time/issues of repairing it (let alone chatting to the CotC). So back out of everything you feel even remotely intimidated by.