Arrange your leave/resettlement etc so you have it all in a big lump at the end. Then crack on with your new job when you like. Once you have handed in your 1250 and cleared off station for the last time no-one really cares what you do so enjoy the double pay! I managed 7 weeks of it, but as a previous poster commented make sure you keep some back for the tax man as you will probably underpay.