Ubisoft sent me a beta key and once I registered just now they sent me 3 more keys to share - beta is over next 3 days.
Message reads :- Provide your friend with a Beta Access Code and have them head over here - https://betasignup.ubisoft.com/sjcb
So here's the 3 keys I was sent and there probably more around from others who signed up.
ps. If you take a code then please note which one you use so others don't waste time trying used up codes, cheers