London Pass

When we looked into it pre-COVID, we considered these things: most of the sights that were included were not things we wanted to see anyway; only a few had a special entry system for pass holders; often things that say "skip-the-line" the only line you're skipping is the ticket purchase line, while its the security line that takes the most time, and thats not skipped; you'd have to visit multiple sights every day to do more than a few, and the sights you want are spread out all over the city; the HOHO system is not a good way to get between sights; many of the main attractions, like the British Museum, were free anyway;

So its your call, but we chose not to get them.

These days, many people are used to buying tickets ahead online, so ticket buying queues are shorter than pre Covid times. You don’t get to skip security lines - this is usually the hold up rather than the ticket queue.

The Pass isn’t good value for many people, as the things it gives you access to aren’t necessarily the places you want to visit. You need to do the maths for what you want to see. Many museums and galleries in London are free.

Yes, it gets you into the places listed without paying additional.
No, it doesn’t necessarily mean you skip the line.

One line you skip at most locations is the line to purchase tickets. You can go right to the admission point/security screening. Some locations, such as Westminster Abbey, there is only one line and you will be standing in it regardless.

The pros are ease of use and flexibility. You budget your admissions and prepay them. The cons can be that you only save money if you choose to visit a combination of sites where the entrance fees would be more than the cost of the pass. That is why pricing out admissions of the sites you know you want to go to and comparing is the smart play here. Make sure the pass is a good deal for you.

Don't forget that many of London's top museums are free/donation-requested. The London Pass is of no use to you at those museums. The more of those museums you go to (and many are world-class), the less time you'll have to visit sights covered by the pass. London is unique in Europe, as far as I know, in having so many incredible free museums, which makes it harder for the pass to pay off.