Movie goers took to Twitter to complain about the slow speed and fast ticket sell-outs on booking sites.
Others were concerned their local cinema would not appear on the website when they attempted to pre-book their tickets.
Odeon cinema, experienced a peak in traffic with movie goers booking tickets for the latest James Bond film Spectre as well as The Force Awakens on the same day.
The company later tweeted: "Fleet Commander: The ODEON galaxy is experiencing heavy traffic but is now returning to normal force levels. Thanks for your patience."
"It's been our busiest day ever for online bookings and we're delighted that by lunchtime today tens of thousands of guests had successfully secured their seats for Star Wars: The Force Awakens. Having removed our online booking fees earlier this year, we knew this morning would be very busy and did as much as we could to prepare," an Odeon spokesman said.
Cineworld and Picturehouse movie theatre also experienced difficulties. A Vue spokesman said it has sold 10,000 tickets in 90 minutes, according to the BBC.
The new film, one of the most anticipated of the year, will hit cinema screens on the 17 December.
Actors from the original trilogy including Harrison Ford, Mark Hamill and Carrie Fisher will also be part of the new franchise.
Watch the trailer here: