Setting up Microsoft 365 for Business for multiple users

Hi,  I'm just looking for a little bit of advise.  

We are looking to migrate from our current provider over to Microsoft 365 and we currently have around 40 users.

I was looking to see if anyone knew the answers to my queries below:

• Is it possible for different users to be on different plans? i.e office staff on Business Standard and home workers on Business Basic?
• I've seen 'Online Exchange' plans online - is this available in the UK?
• Would all users be able to access an internal SharePoint page, irrespective of which plan they were on?

Thanks!