Please help - Bus from Madrid to Segovia

Hi, we’re planning to take a bus from Madrid to Segovia this April and have a few questions:

  1. Will it be cheaper to buy bus tickets in advance? If so, which site do you recommend for purchasing them?
  2. Are there any special discounts for seniors aged 65 and over?
  3. Would you recommend joining a tour, or is it better to explore on our own? If tours are a good idea, do you have any recommendations?

Thanks in advance!