@bakebeans you know that doctor who comes to see you at 2am because the nurses bleeped them as you are getting sicker ? That's an F1. You know that doctor who prescribes your child's pain relief or antibiotic in A&E ? That's an F1.
They are v much fully qualified, but they are very sensible and will ask if even slightly unsure (as will all medical staff). They are clever enough to know nurses know a lot of stuff as they have the luxury of being on a ward for more than 4 months at a time.
Yes a senior doctor is nominally supervising them, but this usually means they glance at the treatment plan.
By F2 they are completely unsupervised and could be delivering your baby at 2am. For £18 an hour.
Pensions do not pay rent or bills now.