Hair help!!

🗣️calling all hair experts!!🗣️

I’m planning to retouch my hair colour at home like I usually do when it fades out but I’ve realised the products I’ve purchased are different to what I’m familiar with.. I’ve never used a developer/lightener before or done my regrowth before, I usually leave that for the hairdresser ahah

These are the products I’ve bought & how the state of hair is currently looking *please ignore my unwashed hair*

Do I use 30vol for all of my hair or just the roots? Do I just use the dye cream on its own on my already dyed hair or do I have to use a developer? Do I use 30vol on my roots & a different developer strength on the rest of my hair?

I’ve asked google but it confused me more & I really don’t want to stuff this up & fry my hair off right before my trip to Japan 😭

Thank you for all your help in advance !! 🫶🏼💓