I agree with Luckgirl, because as she says she's NOT trying to get her booster ANY earlier at all- just trying now to get the date for when it IS due to be had- i mean, she might ring back on that thursday in question and then there might not be any appts till say for example, another 2, or even 3 or 4 weeks- its like when dentist says, 'make an appt for 6months', for example then you leave it and ring at right time to find there's NOTHING for over another month! Only with booster jabs it really does need doing by date given, or immunity starts to go down, and thats not good in these covid times, especially with winter on the way- it may not be such a risk if you are staying in the house, out of (mostly) harms way, till your given appt date- but if you are out & about (no matter what your reason) then the risk is going to be greater- so Luckygirl is quite right, and yes she should be allowed to book the date now, so long as the appt date is on or after when its become due- she's NOT asking to jump any queues, just secure her due date! Whats wrong with that? ! It must be that system is not set up to accept it now, which of course IS nonsense! Especially if there's a human operator who is putting dates in- they should be able to choose it manually now, by overriding the system, so long as the 6months and 1week date is observed.