Loads of great advice here, thanks everyone.
I actually really like the goth look, pale and interesting is my vibe. So all the comments about it washing me out and making me look dead don't bother me, I actually like very pale toned skin with dark hair!
To the commenter who asked my age, it doesn't matter! Age shouldn't hold anyone back from expressing themselves with the styles they enjoy. I don't strive to look younger and I don't fear looking older than I am. Other people's judgements about my age don't bother me in the slightest.
I am doing a 48 hour patch test for allergies.
I have dyed a test strand and it looks gorgeous. Sort of very very dark brown rather than black.
In an effort to judge how tricky removal might be I have tried a colour remover on half the test strip and it seems to have lightened it up to a lovely golden brown so I reckon reversal is possible. My natural colour is golden brown rather than blond and it's lightened back up to almost my base colour.
Of course if I do multiple repeat dyes over many months/years then removal will be more difficult but at least I know I can reverse it if I hate it straight away!