Calling all CC 2011 Conventioneers:
For those of you who will be travelling by train to Cambridge, please take note of buying tickets in advance. If you purchase a rail ticket in advance from a site such as www.nationalrail.co.uk, your ticket will be tied to specific trains.
When buying tickets on these sites, you are presented with a list of train times to pick from. The result, your ticket is tied to those specific trains. If you get to the train station early and board an early train to Cambridge (or back to London or where ever), or get to the station late and realised you have missed YOUR train and board a later train, your ticket is NOT valid for those trains. The ticket conductor can (he may not) charge you again for a new ticket despite you having paid already for your advanced train ticket.
It may be better to wait till you get to the train station and buy your ticket there for your destination. It may cost you more then buying in advance, but at least your train ticket will not be tied to a specific train time. You can save some money by buying a return ticket, don't by one-way to Cambridge and one-way back home, buy a return ticket for the days you need, but do remember you'll have to keep that ticket safe for the duration of your time in Cambridge.
If you wish to puchase in advance, make sure you allow yourself enough time to catch the train you're buying a ticket for. It's better to be sitting at the station watching earlier trains to your destination leave without you because you have to wait for a later train, then to get to the station and realise you've missed your timed train.