I learned in a wagon and drag. Easier to drive straight from a class 2 that’s for sure, however for experience to jump straight in an artic it’s best to learn in one unless you’re willing to pay for extra lessons in an artic once you’ve passed your test. It doesn’t show on your licence which variant you learnt in so an employer asking what you learned in / not hiring you because you didn’t learn in an artic is rubbish, and as has been said, likely you were told this as they only had artics available and wanted your business.
And as for 1:1 vs 2:1, I’ve learnt b, c, c+e 2:1 as that’s how the army does it. You get twice the lessons as you are getting taught directly and also learning from the other student. You also learn from their mistakes if they make any. Plus it’s nice to have a chill out for a bit after driving for an hour or 2 rather than driving constantly for 4 hours as you’ll start to switch off and make mistakes in turn knocking your confidence.
As ever though, the decision is yours to make.