From the Microsoft press release: (note that all prices are quoted in dollars, so probably do a one to one conversion for UKP? Exact details are 'in the coming months')
Store more with OneDrive 100 GB plan—We’re increasing the amount of storage in the OneDrive standalone plan from 50 GB to 100 GB for the same $1.99 per month. That’s enough space to store over 50,000 pictures (at 2MB per photo). This new plan is perfect for automatically backing up your phone’s camera roll and scanning and saving documents, receipts, and more right from your phone. You can also use it to back up your files and share and collaborate on documents. This new plan will roll out soon. If you’re currently using our 50 GB plan, you’ll automatically get 50 GB more storage added to your account at no additional cost. For more information, see OneDrive plans.
There are then new layers on top of your existing Office 365's 1TB:
Get additional OneDrive storage as you need it—Your Office 365 subscription starts with 1TB of OneDrive storage, and many people have asked for even more storage. Today, we’re announcing OneDrive additional storage, which lets you add more storage—as you need it—to your existing Office 365 subscription. You can add storage in 200GB increments starting at $1.99 per month, going up to 1TB of additional storage for $9.99 per month.
If you need 2TB of storage, we now have an option for you. Pay only for what you need and increase, decrease, or cancel your additional storage plan anytime. OneDrive additional storage will be available in the coming months wherever Office 365 is available.
The 'Personal Vault' feature is described thus:
Personal Vault is a protected area in OneDrive that you can only access with a strong authentication method or a second step of identity verification, such as your fingerprint, face, PIN, or a code sent to you via email or SMS.1 Your locked files in Personal Vault have an extra layer of security, keeping them more secured in the event that someone gains access to your account or your device.
Plus, this added security doesn’t mean added inconvenience. All your documents, photos, and videos in Personal Vault are easy to access on Onedrive.com, your PC, or capable devices.
Personal Vault adds to the robust privacy and security that OneDrive currently offers, including file encryption at rest and in transit, suspicious activity monitoring, ransomware detection and recovery, mass file deletion notification and recovery, virus scanning on download for known threats, and version history for all file types.
Just enter a PIN, or use your fingerprint, face, or a code delivered by email or SMS1 to unlock and access your files—no need to remember multiple passwords. Additionally, Personal Vault can be unlocked with the Microsoft Authenticator app. Whichever way you choose, unlocking is quick, convenient, and helps secure your data.
You can use the OneDrive for mobile app to scan documents, take pictures, or shoot video directly into your Personal Vault, keeping them off less secure areas of your device—such as your camera roll. It’s easy to scan important travel, identification, vehicle, home, insurance documents, and more directly into your Personal Vault. And you’ll have access to these documents wherever you go, across your capable devices.2
Personal Vault uses more than just two-step verification to help keep your files safe and private. On Windows 10 PCs, OneDrive syncs your Personal Vault files to a BitLocker-encrypted area of your local hard drive. And like all files in OneDrive, the contents of your Personal Vault are encrypted at-rest in the Microsoft cloud and in-transit to your device. For further protection on mobile devices, we recommend that you enable encryption on your iOS or Android device. Together, these measures help keep your files protected even if your Windows 10 PC or mobile device is lost, stolen, or someone gains access to it.
In terms of availability, Personal Vault will be available 'by the end of the year', with limited space for non-Office 365 users and unlimited for subscribers. Note that none of this affects Windows Phone 8.x or Windows 10 Mobile though, since the OneDrive clients for these are no longer under development. However, it should be noted that your connections to OneDrive are already secure, so in theory there's no need for a 'personal vault' in the first place.
But more security is always better, plus it does mean that someone looking at your laptop or picking up your unlocked Android or iOS phone (e.g. a colleague or family member) won't then be able to go into your OneDrive and browse your most secret files.