In Britain, basic medical training takes 5 years as an undergraduate, after which there is a further year as a 'pre-registration doctor' before you are registered as a fully qualified physician (during this year, although you are officially called 'doctor', your responsibilities are very limited and the sort of jobs you are given to do are pretty basic- far less than even an experienced junior nurse would be allowed to do. However, you may be called upon to assist large teams with more important tasks in an ancilliary capacity). Once this year is completed, GP training takes a further 3 years- this involves 2 years post-graduate learning, plus a year's hospital work as a new junior doctor.
However, most health authorities and trusts like GPs to have a certain minimum level of hospital experience, so a newly trained GP may well find themselves working part-time at a health centre doing minor jobs under the close supervision of an experienced colleague, whilst spending the rest of their time clocking up more experience working in a hospital. Even when they finish doing this, new GPs are closely supervised for several more years until they begin to take on serious cases, or emergency calls.