Hi
Depends on the game as to where you buy the tickets, but if you can get them from the Lords website then go for it. You could also try the ECB site, Ticketmaster etc - will partly depend on who is playing etc.
In terms of access, Lords is pretty good. The staircases are pretty wide and the stewards are normally quite useful in terms of getting to your seat.
They split all the spectators according to which stand/area they’re in so you just walk round till you get to your staircase.
Maybe your dad may benefit from having a seat near the top of one of the staircases so he doesn’t have to walk down and get past many other people?
What are you going to see?
Happy Birthday to your dad too!