Tim Roll-Pickering wrote:
Now here's the toughie - where can you get NR extension tickets on top of
travelcards on Oyster? I sometimes have to pop beyond Zone 6 in south
London.

You'll need to do the same thing as when you had a paper Travelcard,
i.e. get an NR extension ticket to cover your journey. Such tickets are
available from any manned NR ticket office. As most of these offices
don't have Oyster readers, you'll need to show them your paper Record
Card (issued at the same time as your Oyster), which proves what zones
your Travelcard covers. They'll then issue with a ticket from 'Zone 5
boundary' (or the edge of whatever zone your Travelcard covers) to your
destination.

The same principle applies when you're travelling in London, but out of
your zone. NR doesn't do zonal ticket extensions (ala the Underground)
so you need a specific extension ticket, purchased before your journey
(unfortunately no NR ticket machine I've come across is able to do
this, so it must be from a manned ticket office).

The only difference is on a few NR routes where Oyster Pre-Pay is
accepted. These routes are listed on the lower right hand side of this
page:
http://www.tfl.gov.uk/tfl/fares-tick...05.pdf#page=12

Eventually, TfL wants all London rail services to participate in
Pre-Pay, so travelling out of zone, within London at least, would be
much simpler.