Chances of upgrading on VS45

Hi y'all!
Always flying in UC but flying next monday on the VS45 LHR-JFK in PE (H) due to someone else making the booking for me. I couldn't find this info so just checking: is there any way you can check beforehand what the chances are there will be miles or money upgrades at airport. Is this usually a full/busy flight in UC?
And would anyone advise a time to arrive to obtain best chance to be getting the opp to do so. Far in advance or closer to flight time? Will be at the CH so if it's not offered at check-in would it be smart to tell the lovely ladies at the ch if they could keep an eye on potential upgrade poss. or do they not have the access/ possibility to do so?
Thanks!
Always flying in UC but flying next monday on the VS45 LHR-JFK in PE (H) due to someone else making the booking for me. I couldn't find this info so just checking: is there any way you can check beforehand what the chances are there will be miles or money upgrades at airport. Is this usually a full/busy flight in UC?
And would anyone advise a time to arrive to obtain best chance to be getting the opp to do so. Far in advance or closer to flight time? Will be at the CH so if it's not offered at check-in would it be smart to tell the lovely ladies at the ch if they could keep an eye on potential upgrade poss. or do they not have the access/ possibility to do so?
Thanks!