Any hairdressers on the board/extension advice?

I want to get extensions. I already have long, very thick hair mid-back length, but want rapunzel hair down to my bum, can i just apply hair extensions to the underneath of my head to extend the hair? If so what sort of length should i be looking at? Also i don't know whether to get clip-ins or glue ins.
Also, synthetic or real hair? My hair is naturally wavy and in the rain or humid conditions it goes curly, so i need something thats going to hold a natural wave without styling (i never do anything with my hair except plait it or give it a good brushing) - will the extensions show if i use clip ins if i plait my hair?

Thank you!

Extensions advice

hi i do balmain hair extensions called double hair they are like wefts but they are bonded on to your own hair you can also have them taken out when they grow down and then use the same hair to replase them every two to three months the hair is gorgous quality and if looked after it will last you years you have to pay a lot when you have the first set done then after that you are just paying to have them rebonded just look up to see who does balmain hair extensions in your area for a consultation they will advise you about lenth and color ask for double hair good luck hope i helped