Create new website in Pt language by copy of an existing one

Hello
I have a business operating in London; the website is www.alisonlawsoncentrelondon.co.uk, I intend to extend the business to Portugal and I'm considering 2 options:

-buy a new domain to reflect the new location (such as www.alisonlawsoncentrexxxx.pt) and create the new website as a copy of www.alisonlawsoncentrelondon.co.uk, in Portuguese.

-or just add a new language to the existing website and associate it with www.alisonlawsoncentrexxxx.pt. The advantage of this solution is that the new business in Portugal would have more credibility, as it would be associated with an existing business.

Please let me know a cost estimate for each option if possible.