Screening Service: -
The screening service is a national program managed by NHS breast screening programme (NHSBSP). Screening service is managed locally by regional centres and delivered through clinics and mobile vans for women without any breast related symptoms in certain age group (currently 47 years to 73 years) and is by invitation on a 3 yearly bases.
You shall receive a letter asking you to attend for screening in your area and the letter would provide details of site and contact details so you could decide what is convenient for you. Screening is performed via X-rays (called mammograms).
The screening mammograms are sent to regional centres for specialist reporting and to decide if you need further assessment. If your screening mammograms are normal then you would receive a letter to confirm this and you would have the next routine screening mammogram on 3 yearly bases till you reach 73 years of age. After this, automatic invitations stop but you could call your regional centre in 3 years and book an appointment for your mammograms. Here is further information about invitation to a screening programme.
https://www.gov.uk/guidance/breast-screening-programme-overview#screening-invitations
If you have moved in to a new area and had a recent mammogram in any other UK centre, let them know and they will try to obtain your previous images for comparison. If you had any mammograms anywhere in Europe/ overseas and have them with you as films or a CD, you could provide them to your screening centre for comparison. If you are moving out of an area or country, you could ask for your most recent mammograms with report but your local hospital might ask you for a nominal fee to do this. If you had a mammogram between the 3 year screening interval for any reason then you could postpone the screening mammogram to keep the gap to 3 years.