One of the problems with British railways is that they think bank holidays are a great time to do engineering works, close lines and cause confusion and chaos. This is simply madness. On Intercity routes they are the absolute busiest days. They are populated by people who don't go on trains very often so they won't be familiar with alternative routes. People can't go any other time so can't alter their journeys to compensate. It also costs loads more money to hire people to do the work that at other times of the year.
If they closed routes during normal times, people who take the train regularly could see advanced notice saying "the train won't be available on xx days next month, please plan accordingly" and they could plan to e.g. work from home that day, take the car or a Taxi to another station and catch a train from there, find a bus or coach service, or take the Rail Replacement bus, but allowing the extra time it would take. They could be compensated with extra time on their season tickets and could appreciate the improvements in service.