So, this an interesting one. Realistically, you shouldn't be allowed to book on flights without BA metal; however, there are ways around this if you find a VERY good TA (not Amex Travel!).
In terms of ticketing, it all depends on how you book. If it's done as a standard booking, it
may ticket quickly. On the other hand, I've used a TA and taken advantage of special 'contracted' fares where the ticket was booked months in advance, but issued closer to departure, allowing me to retain a high level of flexibility, which has come in very useful on more than one occasion!
