Yeah your right about one thing if you dont put a set of good pads in and fluid in you should not go to the track. Its dangerous and will destroy your current breaks. Rubber is not as important especially if your just starting. In fact good rubber only increases the demand for better breaks. You will be surprised how far you can get on a good set of pads and fluid. I would recommend a break upgrade ie calipers and rotors for Sandown only when you start making more that 260 - 280kw and using semi comp rubber. Driving a car with std pads and fluid on a track is a skill that a professional would struggle with let alone an not a amateur.
You can never get enough training. I have always found that the more you learn the more you realise there is to learn. In fact that was actually said to me by Tomas Mezera a former racing driver even he feels ther is so much to still learn lol. A comment like "who doesn’t know how to go round a corner fast" is pretty silly and an attitude that is defiantly not ideal to better your driving. Sandown actually has many corners which have little secrets and you can make up a lot of time by the use of an instructor. A common mistake for new comers is turning in too early and not sacrificing the second last corner. Driver training sessions are also useful to get good advice about seating position, track etiquette, gear selection, braking techniques and stops you from forming bad habits.
"Who doesn’t know how to take a corner fast?" Me for one but it won’t stop me from learning.
I just had a look at the forecast and it not looking great. I will be nothing short of devastated if its a rain out.