My colleague and I just went to the online booking which allows you to book a booster once it has been 6 months since your second jab. It won’t allow you to do it any earlier. We didn’t need to be called as we’re noted as healthcare staff from the first time around. Have since been contacted by my GP and the local hospital Trust to invite us to book so it obviously flagged in their system as well. We’re in Leeds and not in any other priority group if that helps. As with others above, I didn’t need to show any letter / ID this time because it’s on their records.