Google flights found this little gem for me today.
320 BA Tier Points and a couple of nice BA rides, and you can still be in the office on the 3rd, when the UK returns to work from the holidays. This avoids any need to travel to Europe to start the trip. You can add segments on the outbound for £100. Remembering that if you use the BA web site you only book in Business Class on American domestically and so only earn the lower level of Tier Points.
Or cash in 30,000 Avios and get it for £876 on the BA web site: