Welcome to the Q&A Forum

+1 what Keri and Andriy have said. I would only add that you can still buy additional domains and redirect them to your core site. e.g. your single site sits on site.com. If you wanted to "glocalise" your appeal then you could promote site.co.uk in the UK in advertising campaigns and have it 301 redirect to site.com. This would protect your brand, and also gives you the opportunity to localise the experience on site.com if they were referred via site.co.uk, and configure things like setting correct local currency. It really depends on how important having a local appeal is to your client. George @methodicalweb