It's hard to find where it specifically says anything about this, Can a model shoot, and then melee a unit after? or is there a rule where its either you shoot or you melee a unit, but not both.
You can do both The only restriction is : if a shooting unit is already in melee, they are force to shoot on that unit only
you can do both, you just follow the turn sequence (core rules, page 7). Page 14 details the "attacks" and there's nothing that implies you cannot do both. just to help @payten johnson , the reference is core rules, page 12, 10.1.1