The Bodleian Libraries have extensive printed map collections as well as excellent digital mapping facilities.
You may also find the Bodleian Library Map Room website useful.
Digimap is a key resource for digital mapping and includes historic Ordnance Survey maps from mid 1800s to the early 1900s. Maps can be viewed on screen, saved for printing or downloaded as data for use in GIS. If you have not used GIS tools before, you are advised to contact the Map Room staff. Also, please note that a Single Sign On is required, even if you are using a PC connected to the Oxford network.