Steve,
Infinity is just BT Retail's brand name for FTTx - as I understand, if you are on an FTTP connection you get Options 3 & 4 available when ordering which are the >80Mbit speeds.
With regards to what is happening, it's nice to see HiE providing more information now regarding what's happening and roughly on what timescale. Previous discussions I've had with HiE & Openreach have got the simple answer that FTTC comes first, followed by EO lines & then FTTP, but no guarantees on what happens when beyond the normal FTTC.
For your situation, I would expect that you would get a cabinet dropped in at the exchange rather than FTTP as I think the FTTP stuff is being reserved for the out-of-town lines where it's too far for FTTC to work. However, I would be very happy to be proved wrong and to see FTTP happening to some in-town lines as I've got a few customers in the same situation as you in Elgin, Forres and Lossie who would kill for 330Mbit.
Rob.