Any medications that are banned - which is tricky because there isn't a published list. Codeine is a big no no and funnily enough poppy seeds for baking (which you didn't mention). If you do have prescrip meds you are bringing with you, bring the script from your doctor and check with the Qatar Embassy in your country to see if it is banned (some items are classed as narcotics and are banned and you might possibly be arrested - it has happened in the UAE in the past).

You can buy booze here once you have an RP and a letter from your employer allowing you to apply for an alcohol permit.

As for things we miss, that's very individual, maybe come up with items YOU can't live without and we can advise if they're available here?