Everyone I meet tells me I definitely look over 18 without question as I'm a very hairy guy, have a full beard, deep voice etc.
I just want to know if I can get away with getting into coffee shops as I will be with people a lot older than me and they will be getting in no problem, if I am unable to go in I wouldn't really mind as I'm not too bothered but would they be able to buy the weed and bring it out to me to smoke privately?
You can smoke it, but the issue is that you won't be able to buy it.
The only legal places to buy weed are the coffeeshops, and they won't sell it to anyone without seeing valid ID first. The only ID they will accept is your passport, which if you attempt to change in any way, you will render invalid.
And buying from dealers on the streets is not smart, you'll most likely end up paying extortionate amounts for kitchen herbs.
You won't even be allowed into coffeeshops! You will be asked for ID, and the only valid ID is your passport. When staff see you are under 18 you will be told to leave.
So your older mates will be happily smoking, and you'll sitting outside by yourself!
As far as I know, you have to be 18 to purchase weed from Coffee Shops (and MUST be able to provide ID) so you wouldn't be able to actually buy it yourself or smoke it in the actual Coffee Shop.
First you must be 18
Second they are getting very strict about selling to tourists
Third no one can legally buy it and give to you to smoke in private, that would be a jailable offense if caught
Not legally. You're too young to buy your own and if you ask someone to buy it for you they would be breaking Dutch law.
No. You need to be over 18 and show ID.
http://www.amsterdam.info/coffeeshops/
EDIT. No one can buy and bring out for you legally.