If you're planning to use it in the UK later, then the power is no issue. Both are 230 volts 50 Hertz.
Even if you plan to use it in the USA, you'll find that most power supplies are happy with 110 volts 60 Hertz. The worst you could need is a 110 to 220 transformer (readily available) - but I doubt you will.
Just plug in a UK keyboard, and switch the keyboard settings to match.
You may need a Portuguese speaker to help you switch the language and units etc bits to English - all the menus will speak to you in Portuguese when you start (unless the shop set it up in English for you).