Book direct with Green Lion if possible

I've just returned from a trip to Cambodia which included the Global Nomadic "Volunteer Teaching -Teach in Cambodia" project in Samraong. Whilst I recommend the programme, which is teaching English in Greenway Primary School run by Green Lion, I can't unfortunately recommend Global Nomadic.
Some background information on the project is that in Cambodia primary school children go to state schools for half a day - either a morning or afternoon session. If their parents have sufficient funds, they then pay for their children to have additional private lessons.
The Greenway School provides those additional English classes for students whose family earns less than $100 per month. From what I gathered while at the Greenway School, the English classes are free to its pupils as the school is funded almost exclusively by donations. In addition, it is almost entirely reliant on volunteer teachers.
I enjoyed my time on the project, but despite being a seasoned volunteer I was very apprehensive prior to joining given the lack of information received from Global Nomadic and then the contradictory information I received direct from Green Lion (Green Lion was correct).
So, some things that I wish I had known prior to signing up for the project which I hope may assist future volunteers (some of the following contracts the information provided by Global Nomadic, so is solely based on my experience):
• Travel to and from the project is very easy and by taxi. This takes 2 hours from Siem Reap and costs $30. Taxis can take up to 4 people, so the $30 is split between passengers. My transfer to the project was included in my payment to Global Nomadic, but I knew I'd have to make my own way back. Global Nomadic told me that I'd need to catch a bus back to Siem Reap - there are no buses!
• The transfers to the project are only on Sundays. I was told that I'd be collected on Saturday and arranged my accommodation accordingly. Shortly before leaving the UK I had to phone Global Nomadic to find out details of my transfer (my email hadn't been responded to) only to be told that the transfer was on Sunday
• Taxis do leave Siem Reap after 2pm - my transfer arranged by Green Lion was at 3pm. Taxis also leave Samraong for Siem Reap on Friday evenings after school finishes
• The accommodation is in a secure "compound" with several other volunteers. It's basic, but nice. There are 4 volunteers per room each with its own bathroom (although there was often little or no water from the shower, a problem that I think has now been solved)
• The accommodation is, I would guess, 3 kilometres from the school, so travel to school is by bike. I didn't know this until I arrived and was very nervous about cycling on roads without a helmet and no lights (I refused to cycle at night which limited some of the activities I could take part in). My advice is to bring a helmet and lights
• I'd also suggest buying a full rain poncho in Siem Reap for about $5, an umbrella or jacket suggested by Global Nomadic wouldn't be much use cycling in torrential rain. You'll also need clothes that cover knees and shoulders when teaching. I didn't need water purification tablets as plenty of fresh drinking water was always available at the guesthouse
• We taught mornings and afternoons - not the 3 hours advertised but 6 hours per day including breaks. This was from 8am - 11am and again from 2pm - 5pm. It was very hot midday and gets dark soon after 5.30pm so I had very little opportunity to visit the local area which was a real shame as I thought I'd be free every morning or afternoon and that I'd have the Sunday to explore before the project started
• The project does not ask for resources, but if I had known that whiteboards are used (not blackboards), I would have brought out some refillable coloured board markers and ink to supplement the single coloured pen which was supplied
All in all it was a good experience but I'd suggest booking direct with Green Lion if possible.