On 29 October the new airport in Istanbul is due to open with flights transferring from the existing Ataturk airport between 29 and 31 October. During the transition period, flights are expected to operate simultaneously from both airports.
You should allow sufficient time for check in, transfers to onward destinations and for potential transfer between the two airports. If you have any questions regarding your flight you should contact your airline for information.
Restrictions on carrying large electronic devices in the aircraft cabin on flights departing from Turkey to the UK, have now been lifted. For more information and advice about what items you can take into the cabin on your flight from Turkey to the UK, contact your airline or travel company.
Source: www.gov.uk (abridged)