Trains to London Bridge are much less crowded (though with annoying gaps in timings) and obviously can transfer to Jubilee/Northern. So less fractious than the Overground to Canada Square) - but of course L Br is Zone 1 whilst Can Sq is Zone 2.

The lack of interchange at London Bridge for Waterloo East / Charing Cross from Jan 2015 for a year to 18 months will be a nightmare and expect many more posts on this later in the year! Finding out alternative train routes e.g. from Catford, Crofton Park, Penge East, Lower Sydenham etc may make more sense than trying to cram onto even more crowded tube / Overground. Or prepare for a brisk, lengthy walk to/from London Bridge.