Recently we announced that o2 UK are looking to bring NoDo to customers early April, now we can confim this with the above tweet on their Twitter profile, which clearly states they are expecting to begin the roll-out on April 5th. Fantastic news for all o2 WP7 customers.
One thing that should be noted is that the updates are all being distributed gradually, and isn't as bundled like iOS. You may be on o2, you might not receive the update for another week, but it will come.
Source: o2 Twitter