If you have a big budget obviously you could get everything/most of the things they use on you.
Make sure they are aware of your skin type like if you have oily or dry skin because its important they use the correct primers etc.
I'm a fan of their primers I have been a long term user of the studiofix foundation, concealer, mineralise skin finishing powder I also would recommend their lipliners, eyebrow pencils n eyebrow gels. I have used their eyeliner, mascara and blushers but I think you can go for cheaper alternatives.
Obviously tools are important too.. Their brushes are very good but expensive.
I love their matte lipsticks but I agree that some shades (rubywoo) can be very drying and unforgiving if you have dry cracked lips.
I tried their bb cream before, did not re purchase, I have oily skin and it wasnt a great combination, also I like buildable coverage.
Hope that helps and have fun. Also if you do not like the product do not feel pressured to buy, you will probably be unable to return it. Also, when they swatch your foundation look at yourself in natural light.
Also try and observe the technique of how they apply your makeup.