If you subscribe to Netflix or similar paid streaming apps and find that they offer little of interest to you and at increasing cost (or too many ads), you may want to consider PBS Passport as an alternative. We've trimmed a number of monthly subscriptions from our viewing diet and have found that Passport offers a surprisingly deep offering of British (and other international) series, much like Britbox, as well as many other series and specials. We make a $10/month autopaid recurring donation, and we're very happy with it.

Excerpts from: help.pbs.org - What is pbs passport

Passport "is a member benefit from participating PBS stations that gives eligible donors and supporters extended access to an on-demand library of quality public television programming online. The PBS Passport library features episodes from popular programs, including American Experience, American Masters, Antiques Roadshow, Nature, NOVA, and Masterpiece. In addition to these signature series, the library is full of public television’s acclaimed arts, science, history, and lifestyle programs; including How We Got to Now, Earth a New Wild, Austin City Limits, and a rotating selection of films from Ken Burns."

Each local PBS station "can set their own qualifications for Passport, but most stations give the benefit to members who donate at least $60 a year, or $5 Sustainer/Ongoing-monthly gifts. For the most accurate information, please contact your local station or visit their website."