Most estate agents will offer Home Information Packs for free and look to claw back the cost through higher fees or a withdrawal clause.
The problem is that agents cannot tell their clients this yet as most are undertaking "sell before June to avoid the cost of a HIP" marketing campaigns. These campaigns wouldn't have much of an impact if the packs were going to be free to vendors.
Expect announcements from a rash of agents offering free packs in the first week of June.