No no no no no, the only really effective places to train at your level are Giant Spiders (L50, 3rd Level of the SOS) or Fleshies (2nd Level of SOS). For your level you'll want fleshies. Fastest exp F2P. Lesser Demons are terrible for training in F2P. You get hit too much, so you spend too much time getting food, they're high level so they're harder to hit(This coming from a guy with 93 attack) which, again, nets you less exp. Finally, they're often crowded, making things even worse.