Glad it went well, OP! Talk about a 'phew' moment.
Re car seats, oh Lord, I still have trouble even after plenty of practice. However the worst was when dd once phoned from the friend's house in France where she was staying with little Gdcs - she needed to get an earlier flight home, the weather was awful and baby Gds wasn't well (he had a history of bronchiolitis).
Trouble was, she'd flown from Stansted, the earliest flight back was to Gatwick - and she'd left her car at Stansted!
We had one car seat, so I had to zoom down to Halfords for another and tell the very nice man I needed a baby seat that was absolutely simple for me to install in a hurry.
And I had shingles!!!
But thank goodness I managed, picked them up, drove them home - an hour and a half from where I live. And little Gds was not too bad that time, though he'd been in hospital before with bronchiolitis, and would be again.
It was poor old son in law who had to trek to Stansted to,pick her car up later.