From the BBC booth at MCM London Comic Con, we gave a full in-detail look at the Fourteenth Doctor outfit, as worn by David Tennant in the final moments of Doctor Who: The Power Of The Doctor.
That the Doctor changed outfits while regenerating was a new thing, and it has been suggested that this may have been down to the Celestial Toymaker, expected to be played by Neil Patrick Harris, getting involved with the Doctor's switch back to looking like the Tenth Doctor as some kind of meta-nostalgic kick.
It may be worth noting that the tie/scarf worn by Ncuti Gatwa is indeed the one to be worn by David Tennant. How this will work, however, I have no idea.
The MCM London Comic Con (formerly known as the London MCM Expo) is a speculative fiction fan convention held in the London Borough of Newham twice yearly, usually on the last weekend in May and October. The convention mainly focuses on video games, sci-fi, cosplay and popular media from the United Kingdom, United States, Japan, South Korea, France, Italy, and elsewhere. There has, however, been no MCM London Comic Con for two years. Founded in early 2001 by Paul Miley (ScifiShows) and Bryan Cooney (Wolf Events), both well-known organisers within the fan convention entertainment industry, the show has expanded across the UK and Europe. In 2017, ReedPop acquired MCM and all of its events throughout the UK to add to its portfolio, including NYCC, ECCC, C2E2, and many more.