Did I actually go to Mass?

I have had the experience of being stranded in the diocese of Menevia this weekend,and last,due to a "holiday emergency". Instead of my usual Tridentine Mass on a Sunday (and the occasional N.O.when I can't make the long drive). I had the odd sensation of wondering whether the consecration was valid at all. How much can a priest ad-lib before the consecration becomes invalid? Is it EVER invalid?
I have a friend who will never attend the N.O. Mass, as she believes the whole thing is invalid. How does one fulfill one's Sunday obligation if one happens to be nowhere near a Latin Mass, and in Menevia you can forget it?
Can one even ask a priest what the right thing to do is,particularly Fr Dontworryaboutit, who is probably guilty of ad-libbing when it takes his fancy.
When I walk into my local community centre,I am not scandalised. When I walk into a Novus Ordo Church that LOOKS to all intents like a community centre, and spend too much time in confusion,
looking for the Tabernacle, wondering where the kneelers are, trying to be charitable while Mary and Jean have a loud conversation right behind me, I am scandalised. Maybe because this is not a community centre. Even if the Liturgical banners bear a striking resemblance to the pilates posters on the wall of the community centre. Even if the gathering of children for Children's Liturgy resembles prize-giving night at the Tae-kwon-do group, and the homily, like the toastmaster's speech exhorts us all to join in for tea and coffee in the hall afterwards.
Mass confusion.