The Pre-Migration Checklist (under the menu Web Managers > New Web Managers) describes how to prepare you Site Builder site in readiness for the best migration experience. There is no need to dwell on this phase as experience indicates that tidying up you site after migration works well.

If your u3a has a domain name that you want to use for your SiteWorks site make sure you have access to the management facilities for it. Also see My u3a has a domain name under FAQ heading Hosting.