Lead assigned to a Pool of Leads (web enquiries)

Hi All 

Situation 

We have a CRM implementation where most leads are entered directly by the sales person, and should be assigned to themselves as the owner. We also have a number of leads that are created directly from our public website (via webservice integration) that need to go into a 'pool' of leads that the 'on duty' office sales person can pick up (assigning to themselves and thus removing it from the public pool). Only a certain number of users should see each pool (there are around 5 pools matching the different divisions in the business). 

Solution So Far

I have created Books for each of the pools and enabled Books for the company instance. I have made neither Book or Owner a mandatory field on the Lead record, so that from the webservice I can create a lead assigned to the Book (with no owner) and in the user interface (entered by the sales person) they can assign themselves as the owner (and therefore implicitly themselves as the book). I have then assigned the relevant users in to the relevant books and given them 'Full' access to the leads in that Book.