Sightseeing Jan1 closed in rome ?

Hi, I wanted to go to the euro discovery tour starting dec24 to jan6.

I will be arriving in London Dec25 prior to the tour. I was wondering if because it's Christmas, is there anything that will remain open like visiting Big Ben, London Eye, Picadelly circus...all the major attractions ?

Also, according to the schedule, we spend new year's eve in rome. Then the following day (Jan 1) is free for us to do sightseeing. I was wondering if the vatican will be closed that day because of the holiday ?

And one last thing concerning tipping, do we tip are tour manager and our driver or tips is already included in our tour price as writtin in the brochure I think ?

As u can see, its gonna be my first time in europe and with Contiki !

Thank you for your answer in advance !