Between 25 September and 24 October 2014, LOT Polish airlines is operating the Boeing 787 Dreamliner between London and Warsaw, on Thursdays and Fridays.
There is also a special offer on the route. Flights from London Heathrow to Warsaw between 25 September and 24 October start at a very reasonable £128, and the cheapest Dreamliner flight we found was £149.98 (out 10 October, returning 16 October).
The link to book at the discounted prices is here. Note that you will need to make sure you fly on flight numbers LO279 and/or LO280 on Thursdays and Fridays (excluding 9 and 17 October) if you want to travel on the Dreamliner. The LOT-worded offer is here:
(Ignore the £170 reference – flights are available cheaper, as noted above.)
Remember to earn Lufthansa Miles&More points on LOT flights.