Third Age Trust (TAT) has a SiteWorks hosting arrangement in place with a company called Sarah Hayes. They already supply services to the Trust including looking after the main Trust website u3a.org.uk
Of course, u3as can make their own hosting arrangements but otherwise be part of the Site Builder to SiteWorks migration. See f Can the SiteWorks team help if our WordPress site is hosted on our own site? and g Can I use the SiteWorks theme and plugins on our existing WordPress website?