Tuscanlifedit, thank you for describing your schedule for a day in Cambridge. I am planning a similar tract. Would really like to visit Fitzwilliam Museum.

In June I expect to spend five days in London solo before joining a tour to Wales. So much to see and do! I would only go to Cambridge on a day when the weather looks most promising.
Good for you to keep traveling even when you have some health issues. Enjoy your trip…

You can find information about private tours in Cambridge at : http://www.visitcambridge.org/official-tours

If that turns out to be too expensive you could do the two hour one.. there will be stops along the way and just drop out if it becomes too difficult.

the As I recall thebus was right at the train station when I got to Cambridge , it could be that its timed that way, but of course a taxi would be fine. and unlike the bus it would probably be able to bring you closer to the city center where the buses do not go.