Hey there Alistair,
Thank you for your post! After doing some research into this, I dont't believe bookmarking is possible within the current sites product. However, there may be a way to get analogous functionality by implementing menu links in the header. Each menu link would lead to a certain portion of your site. I have yet to test this (not quite sure if you can generate URL's that go to a certain location of your site) but it may be worth a shot.
Please let me know if this helps!