Welcome to Vodafone Community
Whether you are on Fast Path or not is decided by negotiation between the OpenReach (ie not VF) cabinet and your modem/router (VOX3 or VOX2.5). That negotiation gets tweaked at various times, depending on how well your connection is behaving - so at some future point, it may return to Fast Path.
See: https://kitz.co.uk/adsl/interleaving.htm for details.
As for latency, you can still use various speed test sites to check for the unloaded latency, and many sites can also tell you the stressed/loaded latency for your connection - Just be realistic, many of the figures you see gamers especially posting regards latency are braggs and don't reflect the real world.