If you want to drive in a foreign country, you need to possess a valid driving licence. For some countries, you may be able to drive for a limited period with just your national driving licence (i.e. driving on a UK licence is permitted for a limited period in certain other countries). If you apply for a driving licence in any other country, having your UK licence will often exempt you from any driving test. Therefore, take your original full national driving licence.
Since 8th June 2015, your paper counterpart driving licence has no longer been valid, but don't destroy it just yet. In theory, you should only need your photocard licence from now on. But it could present problems if you're hiring a car around the world, as your driving endorsements and penalties are on your paper licence. It is suggested that you keep your paper licence for a bit longer just in case.
Further information about the UK driving licence and what it entitles you to drive whilst within or outside the UK can be obtained from the UK Driving and Vehicle Licensing Agency.