I would appreciate it if you read the whole description, I know it's long, but please help me!
I want to dye my hair vibrant purple (I already have the dye - brand: Adore)
Btw, it's this one:
http://www.sleekhair.com/ado02-116.html
and I tried the tips of my hair to see if it would show up on my faded black hair, but it didn't at all. So, I am considering to buy some bleach or pre-lightening kit to dye my hair. I want something that's not too damaging and something that's available in most UK drugstores like Boots and Superdrug (no online stores). So, any suggestions?

ALSO, PLEASE EXPLAIN THE PROCESS OF BLEACHING FOR YOUR RECOMMENDED PRODUCT AS I AM CLUELESS.

AND TELL ME WHAT THE COLOUR WILL TURN OUT AFTER THE SEMI-PERMANENT DYE WASHES OUT. WILL IT BE BLONDE (AS IT WAS IN THE PROCESS OF PRE-LIGHTENING???) I REALLY NEED TO KNOW ALL OF THIS!
THANKS!!! :D