Generally, most prescribed opiates contain an NSAID (non steroidal anti inflammatory), both to aid the intended purpose of the medication, and to prevent abuse - hence why over the counter painkillers generally have around 10mg of codeine and paracetamol/acetaminophen, to prevent anyone from being able to take enough to get high without doing themselves serious damage.
If they do have something other than codeine, you can also do a cold water extraction to separate the codeine and the NSAID, but given that you're a first-timer and they're 30mg tablets, you don't really need to.
They might just be codeine though, which is even better!
If they're just codeine, with nothing else, then you can push it a bit more, as there's no risk of damage to your liver from the paracetamol/etc. Codeine can make you pretty itchy, so taking an antihistamine before not only relieves this, but makes the codeine come on a little stronger.
As always though, don't be silly, try 4 tablets and you should get a pretty decent buzz. Then just use your brain from there if you want to try again.