Opening Times: Depending on the season, the majority museums in London open between 8 and 10 AM and close between 7 and 8 PM. It's best to always verify the opening hours on the official website before you go. Be aware that almost all museums of London are closed on Mondays.
Free Tickets: On either the first or last Sunday of each month, a number of museums in London grant free admission. If you're on a tight travel budget, find out when free entry is permitted by checking the official website. Keep in mind that on some particular days, it does get packed.
Discounted tickets: The majority of museums often provide reduced admission for students, children, retirees, and people with disabilities. The exact cost can be found by checking with each institution.