Guildford isnt really a holiday area, so cottages will be fairly limited in supply I would think though this looked nice

http://www.cottagenet.co.uk/summerhouse.htm

Will you have a car? because otherwise you'll likely find yourself stuck and unable to do much exploring unless you go for something closer to the town centre.

I think you have a number of options - including staying in Guildford, staying in one of the small villages near Guildford and driving to work, or staying at a midpoint between Guildford and London (such as Wimbledon or Battersea) and commuting by train. This would enable you to comine your trip with sightseeing in London.