Sorry to disagree with NickB, but a two hour journey on a TER will not be burdensome and it is normally cheaper than TGV (if one is available). You may want to look for specials on the SNCF site such as those for two travelling together which offer additional discounts. Book early. Note: TER normally are open seating not reserved as are the TGV.

Having never ridden Ryanair and probably never will, I cannot comment directly upon its Paris landing site. I have heard it is a long distance from Paris and fairly expensive to reach. www.google.com should provide contemporary info on getting to an from Beauvais.

Enjoy you trip.

Edit to add: http://www.aeroportbeauvais.com/bus.php?lang=eng. 13$E and show up 3.5 hours before the flight may cause you to look at options other than Ryanair. There are a number of carriers that fly into both CDG and ORY which are easier transportation options to connect to Tours.