Going back to natural colour?

Heya,

I have just had a mammoth wardrobe clear out and the vast majority of my summer stuff are red/pink/orange/yellow (+tons of black/white) but as I currently have pretty bright red/pink hair all of these clash and I can't wear them!  We are in the middle of moving house so I have zero spare cash to by loads of new clothes so was thinking about going back to a more natural shade for the summer (probably back to something bright for the autumn/winter as those clothes are mostly black/grey)!

Problem is I have no idea what kind of colour would be best...I was thinking possibly a nice rich warm mahogany but not sure if it might be a bit too dark for my naturally pale skin?  My natural colour from MANY years ago is a very boring and dull mousy brown.

Also, what's the best way to go about it...I have about 2weeks left of my current colour before the fade and my roots/greys will need redoing - do I just put a box dye over the top of that or would it be best to strip/bleach bath then use a semi such as Adore Mahogany/Mocha over that?

Thanks
A xXx