Hi Tony, ideally you should give readers an indication as to what race time suits you best. Do you want to race every day? Would you prefer to race one car or two car teams? What Race distance or are you not fussed?
A league host will hopefully respond and steer you in the right direction.
Edit... I just checked your account and see that yes, you won Pro but were not promoted because of lack of numbers. So you're looking for a league with an active Pro tier. Unfortunately not many of them about at the moment but the Devs are promising an imminent update which they say will result in more populated Pro tiers.
You could join my league! We have at least 10 people every day at 4 pm uk time :) and we have I think 28 cars. It’s a single car league though.
Every tier is promoted. Totally up to you and I’m not trying to sell it on ya!
You could also check out formula zero offline. 2 car offline league. Pro has 1 space currently, I'm not sure how many are setting up but there are enough players there for promotion and relegation to be active.
I wouldn't recommend joining quite now as there would be a strong threat of relegation given the car you would be awarded for a mid season join.
The next season will start on Monday 13th January.