Holiday Money

[chrisuk013]

I'm going to Brazil(Rio & Recife) for three weeks. I have a holiday budget of £2,100 ie £100 per day whilst I am there. 
 

Now, Rather than exchange the whole amount into Brazilian R$, how much would you exchange and how much would you keep back put on a travel debit card? 
 

Also, which travel debit card is the best one to use for exchange rates? 
 

TIA x