All advice given in this article is offered without warranty - always check before travelling.
If you often travel by train outside peak times, a railcard will save you money quickly.
Even if you already have a Network Railcard, a Cotswold Line Railcard will save you money if you regularly travel to Oxford off-peak during the week, because there's no minimum fare.
The list of tickets available from Charlbury to London is now very complex. As a general rule, all journeys leaving Charlbury before 8.30am, or leaving London from 5.20pm to 6.30pm, require expensive full-fare 'Anytime' tickets. Cheaper tickets become available in the morning from 8.30am onwards.
If you have a Network Railcard, you may be able to save a little money by buying two singles. For example:
This is especially true if you can get an advance ticket for one of the journeys (see below).
Until recently Charlbury has been mercifully exempt from the pernicious rationale that you should have to organise your travel well in advance to get an affordable fare. Unfortunately, First Great Western has now jacked up on-the-day fares and advance booking is required to get a reasonably-priced long-distance fare.
You can book the fares from any train company website, not just the First Great Western one. (The train company gets commission, so choose wisely!) However, don't use thetrainline.com, which charges a booking fee.
If you're heading to Oxford (or even Banbury) for the evening, leaving Charlbury from 6.37pm onwards, buy an Oxford Evening Out ticket which costs just £3 for the return. You'll have to ask for this on the train - the Charlbury ticket machine can't sell it.
For Birmingham, the Midlands and the north, the best fares are often from Banbury. A day return from Banbury to Birmingham, for example, can be as little as £14.50.
From Charlbury, the quickest route to Birmingham is via Oxford. Don't buy your ticket to Birmingham, but buy it to the suburban station of Stechford instead: this is over £10 cheaper, still allows you to travel to Birmingham, and no-one is going to check if you actually do go to Stechford or not.
If you have a Network Railcard or Cotswold Line Card, it's often much cheaper to buy a return to Worcester using your railcard, and then buy a separate ticket on from there to Birmingham (or Great Malvern, or Hereford, or wherever). Going via Worcester is slower than via Oxford.
For the West Country and South Wales, cheaper and faster trains are often available from Swindon (approx. 45 minutes' drive from Charlbury along the A361).
There is a bewildering number of ways of getting to Heathrow from Charlbury. Here are a few: