Solved

Tier change

Iv got someone who wants to join my league but the elite tier is full, is it possible for an elite to join the pro tier to start off in?

No it's not Paul. He can only join to the Elite tier, unless he gets the relegation to the Pro tier in another league

If he wants to join he has to relegate first, or the host has to kick somebody, but you should only do that when there is a really inactive plauer in the league.
If he stops racing in his old league till he is in the degredation zone (If there is one), he could leave the league which results in immediatly relegation, but he has the risk of being kicked then.

Ok thanks for the reply lads!