Appointments + how to change some front end text and visuals?

The link for my page is http://exit-newcastle.co.uk/make-an-appointment/

I am trying to change the text that is currently “Please select a service” and then below this the text “Please choose a service provider” I would like it to say “Please select group size” followed by “Please choose a game”

There is also two separate buttons for show available times one under each of the drop down menus. I assume they both do the same thing and refresh the schedule but would it be possible to get rid of the first button so there is just one under both the drop down options?