You think that service was busy?
I have put labels on every Standard seat for the 1903 FO from
PAD» once before and as it was short formed even coach E was fully reserved.
As far as im aware, every seat with some minor exceptions* is available to be reserved.
As regards you being a season ticket holder, I belive that if you give your local booking office a list of what you want to be reserved on (such as the 09:xx from A to B and the 18:xx from B to A and what dates) they can process them for you in between customers and have them ready for you to pick up at a later time. I know of several customers that do this with local smallish stations.
Dont even bother asking PAD. Far too busy constantly.
Now the official version as per FRPP is as follows:
Seat Reservations ^ First Great Western
Trains on which accommodation can be reserved are shown in the National Rail Timetable.
The seat reservation charge is ^5, except in the following circumstances where reservation is free of charge:
one reservation if reserved at the time of purchasing the ticket;
wheelchair spaces, assisted passengers and their companions;
holders of Rail Rovers.
Reservations are only available to passengers buying or presenting a valid travel ticket. Only one seat reservation per passenger (plus connecting reservation where appropriate) can be made for each journey.
A seat cannot be reserved if no passenger is to occupy it, even if an extra ticket is purchased.
Child Reservations
Where separate accommodation is required for a child under 5, a child rate or flat fare ticket must be held for the journey.
I dont know where anyone gets charged a fiver these days.
*Coach E is normally non reservable, however this coach is used when another coach is missing. Hence the common Reservations for Coach B can be found in Coach E. Also some disabled seats are non reservable.