If you invest a little time or money and if it will stand it thin it out a little. The logs can be sold on (if extracted at a reasonable cost), leave the rest to make habitat piles for the local wildlife,n ( check with your local council to make sure that there are no preservation/conservation,SSSI issues etc etc.  
I am not sure if there is much financial gain to be had from a woodland unless its from opening it up to maybe shooting days out, Paintballing or perhaps trail bikes/pony treks, (this could be dictated by your local planning office, so check first). 
There are grants available for