Arsenal, the Lancaster is probably the most difficult plane to take-off in AH.
I fly them a lot, so here is my best tips.
1) Do not ever attempt to take-off if you see hills at the end of the runway. You will crash most of the time.
2) When learning, use 25% fuel, and no bomb load. It will help to ease you into the flight model.
3) Do not use flaps to take off. They will slow your climb to take-off speed. If you do use them, be prepared to retract them immediately after your wheels leave the ground, or you probably will auger.
4) As tofri suggested, ease your stick a tad forward at about 80 knots to lift the tail up off the ground. This does help achieve take-off velocity.
5) As you approach take-off speed, gently pull back on the stick and once the wheels leave the ground, level, then retract your landing gear.
6) Hold level, if possible, and gain a bit more air speed, then proceed to ease back on the stick and start a painfully slow climb.
7) Once you are about 1000 ft, you should be able to fly normally.
With no load, the Lanc handle pretty well in the air, but with 50% fuel and 14K pounds worth of bombs in her belly, she is like a flying through molasses.
Good luck.