The sandwich and hot drinks outlet will replace the former Natwest Bank space near the Pavillions Shopping Centre.
The shop will have two floors of internal seating for around 100 customers and free Wi-Fi.
To celebrate the launch, the team will be offering a sneak peek of the shop and free lunch for the first 400 customers on Thursday.
Over the past year, Pret’s national scheme has distributed over three million food items to homeless charities, hostels and shelters across the UK, according to the company.
Work has been ongoing for weeks, with Pret adverts in the windows, as shown in the photo below.
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Below - Natwest bank in 2015 courtesy of Google