score:2
To be eligible for a UK Standard Visitor visa you must show that:
youβll leave the UK at the end of your visit
youβre able to support yourself and any dependents for the duration of your trip
youβre able to pay for your return or onward journey and any other costs relating to your visit
you have proof of any business or other activities you want to do in the UK, as allowed by the Visitor Rules
Source: https://www.gov.uk/standard-visitor-visa/eligibility
You must answer the question about any travelling companions correctly, regardless of whether they need to apply for a visa or not. Include evidence of your eligibility to enter the US (ESTA or visa) with your application, to show UKVI that you can complete your stated travel itinerary.