To whom it may concern, Me and wife are British Citiziens and hold British Passport

and going Cruise in your region in April 2017
On 9/4/17 we will finish our cruise and dock Shanghai at 7.00 AM where we enter and stay at:
Rayfont Celebrity Hotel, 1077 Xietu Road, Shanghai 200032 tel:862131221088
Check in Sun 9/4/17
Check out Tue 11/4/17
Our flight departs 11/4/17 at 8.30 PM Shanghai Pudong Airport
Airline Cathay Pacific
Destination: Heathrow London UK
My question is, as we are only staying less than 72 hours and we do not need ViSA For Entry on the ground of being British citizen passing transit and having a confirmed flight ticket.
How do we apply to get this free transit? Do we have to to apply to the Border Control Authorities at the Entry point or do we have to apply now and where?
We would appreciate very much if you could let us know the answer please?
Thanking you in anticipation for your kind attention on this matter
We are worried about this issue
Look forward to hear from you
Kind regards
Mr. & Mrs. O and F Osman
United Kingdom