I had a situation a bit like this a few years ago, so a few questions:
- do you know where he works now?
- do you have his birth date?
- do you know (even roughly) how much he earns?
- do you know his national insurance number?
All I did, when Ex disappeared (I mean, literally, moved to another city/job and cut contact while I was pregnant the charmer) was handle the pregnancy and everything else myself, then sent him a very polite letter and a few photos when she was a few weeks old, to his work place (only address I had).
The thing is, if he knows ( and from what you've said he DOES - the friend will have told him surely even if he ignored the message), the decision making is down to you now. I decided it was best to assume Ex was never going to get involved and proceed on that basis. He's never met DD (now 2) so it turns out that was a wise idea. He is an adult and responsible for his own choices I've made it clear all along that I am open to contact and even encourage it. His loss as DD is the most gorgeous amazing clever cutie the world has ever seen - and my gain.
The child maintenance people asked those questions above, any/all of the answers will help them make direct contact with him and assess his maintenance obligations - so if he won't talk with you later on, they'll still get in touch if you want them to. They won't start processing maintenance until you can give them the birth date of your child (I tried, that's what they told me) so you won't be able to do it while you are pregnant.
One tip - it's easy to set up an anonymous email address, then use that to set up an anonymous Facebook and Linkedin account. Both are ways to potentially find information for maintenance without him knowing and blocking you / making changes. Another option is a private investigator (not always as costly as you might think).