Hey Rio, I work at Asda on the checkouts in the holidays...
Good you've got the job
You probably won't get much training, my first week of hours was supposed to be training for five days 9-5, but really I had training the first morning and then was put on a till - but not properly, I had somebody there with me in case I got stuck. I think it was like that for a week, then I was put on a till on my own

It's not so bad though, people often guess if you're new, or you can tell them anyway, and then if they're nasty someone else will tell them off
All the vegatable and fruit codes are a pain to remember, I suppose you'd have those too (I work at Asda) but over time you get used to it.