Well, technically you'll need (and want) at least PHP >= 7.1.3.
Statamic 3 will be a Laravel package that supports Laravel 5.6+, which in turn requires PHP 7.1.3. The latest version of Ubunutu (18.04) ships with PHP 7.2, so as long as you have a relatively new server, you should be good to go.
If you need a new host or server, we recommend Digital Ocean. You can run a bunch of Statamic sites on a single $5/mo droplet. It's hard to beat.
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