Lot of misinformation in this thread, hope the below clarifies.
The 500Mb & 1Gb FTTP products are available nationally
on any FTTP provided on a Huawei head-end (As it can have 10Gb GEA cablelinks, whereas ECI cannot).
When you look at the BT Wholesale checker it will show you what BT Wholesale ISPs can provide via their network.
If you see only 330/50 then it is because either the FTTP is ECI backed, or more likely that Wholesale do not have a 10Gb GEA cablelinks in place to the L2S, or sufficient back-haul capacity to provide the service.
There are in fact ISPs (us included) that do and have been selling the 500Mb & 1Gb products for some time, limited to geography.
(If anyone is in the West/East Midlands and keen to consume this product, get in touch).
These are premium products so you shouldn't expect these to fall into the regular residential pricing tiers.
Indeed the £500 install from Openreach is used as a "reserve" put aside for the cost of the XG-PON upgrade when capacity on the existing PON exceeded. There is no (non-trial) installation of XG-PON in the network today.
Hope that clarifies.
Network Architect - Syscomm