DTD / Carwow quotes are competitive in part because the dealer hasn't had the overhead of a walk in sale, e.g. several hours of a salespersons time, back office time, test drive etc. etc.
If you are looking for the full dealer handover experience of covered up car unveil, flowers and fizz plus the choice of a few bits from the accessories cabinet I'd suggest checking with the dealer beforehand as this is again time and overhead which they carry to generate goodwill and in the hope that you'll be back for service over the years and also possibly for your next car - not necessarily the situation with a broker sale.
Get there, pick it up and enjoy the drive home!