No one will stop you and its your decision, however i believe it is still a bit too early for you to learn HR. it might hinder your improvement greatly in the long run (i experienced this when i learnt it at 50k it was a terrible mistake). Usually it is suggested to wait until 4,5k pp till learning HR, however id suggest to wait until 5k. Also learning mods is not a must to getting good and getting a high rank, you can continue nomod for a very very long time. And i mean very long.