Hi all - looking for advice on whether to take Tube/Train, Uber, rent a car, or a combination. We're a family of 4 (2 adults / 2 small children) that will be staying at Kensington Marriott in London for 5 days. Here's what I'm trying to figure out. I have 2 Oyster Cards from previous business trips (one is 10+ year old and the other is 15 months old).

1. How should we get from LHR to Kensington? I was thinking of using the Elizabeth line to Paddington and then transferring via tube to Earls Court. Would Uber from LHR straight to Kensington Marriott be a better/less expensive option for 4 people?

2. We'll be going just around touristy parts of London for about 4 days. What type of tube/train passes should be we buy? Is it worthwhile to get a Railcard (I believe for 30 GBP) just for 4 days? I read there is an unlimited daily pass that can be restricted to specific zones too.