In order to make use of the new superfast fibre broadband, you will need to move to a fibre broadband package. This will not happen automatically!
Your existing provider may well be able to migrate you onto a fibre package for little or even no extra cost, depending on your current package. You do not need to stay with your current provider (unless you are in contract with them).
A good way to find out what deals are available for you is to check out the price comparison sites which have been accredited by Ofcom:
There are other websites that will offer comparisons, or you can go directly to a provider's website. There is a full list of fibre broadband providers on the Better Broadband Oxfordshire website.
Some comparison websites and some providers may be a little slow updating the information from Openreach. So if you've only just been enabled, it may take a few days for the information to flow through.
Be aware that different ISPs (providers) may quote different minimum guaranteed speeds. Whoever you choose, the infrastructure is still provided by Openreach, so any differences in actual speed are likely to be minimal, unless the ISP is limiting your speed.
Once you have selected a provider and a package, it generally takes 2-3 weeks for your new service to be activated as an Openreach engineer is required to make changes to the cabinet. You will also need a new modem as your standard broadband modem will not be compatible. Modems are normally provided by your ISP, though you can buy one separately if you wish.