streamlining email accounts

When I moved from 'Office Small Business' to Office 365, I set up two accounts, one for each of my main email addresses.

I managed to keep one of those addresses the same (info@right.place.co.uk), but, although I'm able to receive mail for the other address (my.name@right.place.co.uk), mail gets sent from  'my.name@right.place.onmicrosoft.com'

I'm also now paying for two accounts, which is surely unnecessary.

QUESTION:

How can I get mail coming to and going from the two email addresses I want with just one account?

Thank you very much,

PaulMWH