If you are entitled to free demutualisation shares, you can either opt to sell the shares immediately or keep them for a year and then decide what you want to do with them. You should be receiving a brochure which lists the options for the SHARES. . Your with profits policy/endowment etc is an entirely separate item. You can't encash the policy until you have received the shares otherwise you lose your share entitlement. I think the float takes place later this summer so you should be able to cash in your policy after that has happened.
I suspect quite a few people will be trying to unload their policies after the demutualision has been completed. Their performance has been singularly unspectacular.
Don't know of a website, but I seem to remember the brochure which accompanied the recent information saying how many shares were being allotted had a telephone helpline number you could phone for more information.