I never watched a single episode of Doctor Who until Jodie Whittaker was announced as the next one. After that, I splurged and deep dove into the series history, over 50 years worth of episodes and spinoffs which took a bit before finally catching up. One of the fun things about that show is that you can just about jump on just about anytime despite the heavy volume of work already out there.
Of course I limited myself to the TV material, not so much the radio or book adaptations. Outside of TV, I've mostly consulted the TARDIS Fandom site. Fandom wikis are some of the best sites to visit when you need information fast on something and TARDIS, the one for Doctor Who is a treasure trove for information.
EDIT: Slight amendment. I do recall watching some Doctor Who as a child, but nothing really stuck with me. It was just this weird thing PBS would air late at night along with Are You Being Served and that show about what planets and/or stars were going to be available for viewing with your telescope over the following week.