Richmond Rugby club allow HM Forces into their games for free. Normally £10.
I found it to be a reasonable standard of play, nice ground with free seating in the grandstand and free parking. Good cheap, chicken/sausage/burger and chips, and Stella on tap
at a decent price.
Tell the missus she can do a bit shopping in Richmond, load up a rucksac with some tinnys and head for the game.
Richmond FC
Edited to add, Virgin Atlantic don't give 10%, Virginholidays however do.