Yes, you'll need a valid passport to travel with TUI. It'll need to be valid for your entire trip and for at least 6 months after your return journey. This applies no matter what your nationality. EU nationals may use their National Identity Card to travel within the European Community, but we recommend you use a passport wherever possible. You'll need to use a passport if you're travelling outside of the EU.
If you're an Irish citizen, you need a full 10-year Irish passport and it must be valid for 6 months from the date of your return to Ireland. Visit the https://www.dfa.ie/.
Just so you know, it's your responsibility to comply with all passport, visa and other immigration requirements for the country you're visiting. Your passport and travel documents must be intact, too. You may not be allowed to travel if they're damaged or they've been tampered with. We don't accept any responsibility if you can't travel because you haven't complied with the requirements.
Going to Turkey?
Just so you know, for trips to Turkey your passport may need to be valid for longer than 6 months after you return. Take a look at our 'What are the entry requirements for Turkey?' FAQ for more details.