Can someone in the UK become an 'online minister'?

It depends on where you are. I believe online ordination is accepted in Scotland but not elsewhere. You need to check with the office that issues marriage licenses. If it is legal you can have your Uncle ordained as a minister at a href="http://spiritualhumanism.org/ordained.php" rel="nofollow"http://spiritualhumanism.org/ordained.ph…/a the Church of Spiritual Humanism.