In Office 365 it appears all users have a mydomain-my.sharepoint.com, however it's totally overkill for us as organisation and I only need a teamsite.
Is there a way to disable the personal (*-my.sharepoint.com) and have the Office 365 redirect to the teamsite immediately?
Yes there is!
Go to SharePoint Admin Center > User Profiles > Manage User Permission.
In the modile dialoge you see "Everyone exept external users" chosen and you just deselect the option Create Personal Site and save the setting by clicking OK.
To redirect users to a team site, I'd update the link using javaScript. But that's unnecessary when the mysite is disabled. Instead add an ordinary top link to the team site you want users to visit.
