I normally travel to work in Westminster from Cambridge on one-day
Travelcards or day returns to King's Cross with bike. No interest in
oystercards there obviously.

However, from time to time I stay overnight at my parents' in Putney and
travel on a Network Awaybreak from Cambridge to either King's Cross (with
bike) or Underground Zones 1/2. In the latter case I need to buy single
tube tickets on top (mainly in the morning from Putney when my Network
Card isn't yet valid).

Can I use a fairly small amount of stored value on an oystercard for these
occasional journeys? I've never bought a carnet for Zone 1 trips because
they are only valid for a year and I don't make 10 trips in that time.

--
Colin Rosenstiel