No. A medical book or a doctor's certificate is not needed to work as a cleaner with us. We clean flats and offices rather than handle food, so a sanitary book is not required by law and we do not ask for one.
What you do need is a passport, a tax number and a willingness to complete training before your first shift. The training takes one day: we go through the cleaning standards, working with professional chemicals and equipment, and the mistakes people most often make.
Safety is covered separately. A cleaner has to read product labels, never mix chlorine with acidic cleaners and work in gloves. We teach that at the start, and it matters more than any certificate.
The one obvious limitation is physical. The work means a whole day on your feet, bending and carrying buckets. If you have an allergy to household chemicals or back problems, tell the manager in advance — some bookings will not suit you.