You can order free HIV self sampling postal kits here.
Not sure which local authority you live in? Find your local authority.
Collect a small spot of blood at home and send it off in the post for testing. You'll be contacted by phone or text with your result in a few days.
For most HIV tests that require a blood sample it is possible to get reliable results from four weeks after possible infection. If you take a test before this your result may not be accurate.