Depends on what you mean by woodland. The AK is the most "woodland" job i have done.
The halfords colours are quite limited. Its basically Tan, Brown, OD and Black. Krylon have 6 shades but i have not tried that paint as yet.
My advice would be spend alot of time getting the prep right.
Clean
dry off
tac cloth
paint in light layers.
To be fair and this may sound like advertising. But if you are not 100% confident in doing it then it is prob cheaper to get it done by someone that has done it before. Can work out cheaper. The paint is around £8 a can, plus the wipes, tac clothes and maskings etc. So a 3 tone paint job would cost around £35 and if you get it wrong its far harder to redo it.