Didn't see that one - it all depends on the number of kids - still waiting back to see if I'm doing a camp for 12 or 24. I'll either want 36m or 72 (assuming 1.5m for the treehugger?)
Personally I'd go with at least a 2m length to start a tree hugger. Some trees are whoppers and that is more likely to provide an always usable length. It can be wrapped around smaller trees several times if necessary which has added advantages.
The quick and easy method is to tie (or sew if you have very strong thread and cross box technique) a small loop in one end of a 3m+ length and then use a carabiner on the hammock for adjustment. Put the tree hugger around the tree and pass the free end through the loop. Take the free end and pass a loop of it, a bite, up through the carabiner and back over the top to form a Lark's foot. Adjust for length, tidy the knot, the webbing in the bite usually needs turning over, pull it down tight on the carabiner and you now have the strongest and simplest integrated tree hugger and suspension in the World. Awesomely easy to loosen and adjust as well, just push the knot towards the carabiner and it instantly loosens regardless of the load, when pulled tight it will never move.
I use this all the time, you can't beat it for simplicity and robustness, ideal for a Scout set-up or anyone. The tree hugger becomes the suspension system or when I use it I just I have massive adjustment as I have the entire length of the tree hugger webbing that comes from the tree to play with and a can clip whoopie slings onto the carabiner as well for fine adjustment and being able to hang between two trees that are forever apart. It saves doing a Marlin Spike Hitch in your webbing as well and damaging it with the Dyneema Whoopie directly on a webbing knot.
Hope that helps.