You would be better buying a UK appliance for her.
The voltage and frequency will be correct .
US appliances are 110 volts 60 hertz
UK appliances are 240 volts 50 hertz
You could use a transformer for the voltage but the frequency would still be incorrect and this could eventually lead to motor burn out.
There is also the warranty.
It's unlikely you'll get a worldwide warranty for the appliance.
Hope this is of some help
Let me know how it goes or if you need more help