I will not fly. We want to go to England next year and are currently investigating ship travel. Cunard seems to be the way at this time.
Another consideration is traveling via cargo ship. It may (I haven’t researched it) cheaper than a cruise or passenger line. It costs about $60 - $150 per day (depending on company and other things).
Cunard would also help you avoid the newly improved (increased) APT - Airline Passenger Tax on your way back. Always look at the cost breakdown of an air ticket, especially to/from the UK. The number of add-on fees and taxes and their size will shock you.