Best hotel for pre-cruise overnight stay - arriving at Terminal 5

There’s a Sofitel at T5. Easy train links to London via picadilly line or Elizabeth line trains. The later is a bit more expensive..

The Soffitel is attached to Terminal 5 by a long hallway. It is about a 5 minute walk once you exit arrivals. It is pricey.

I am going to suggest an alternative plan for your consideration since you mention sightseeing. Stay in London for your one night. You will waste time and your parents’ energy going back and forth to the airport. Stay in the area of Victoria coach station. Then take a National Express Coach to Southampton from Victoria the next morning. Less expensive than a cruise line transfer and allows for spending time in London.

My husband and I are around 80 and had an overnight in London this past spring. We stayed at the Sofitel, which is very nice but is actually a pretty long walk with some escalators/elevators, depending on what gate you arrive into. We were able to check in to our room, and then took an Uber to Windsor. We had a lovely day seeing the castle, eating fish & chips, etc. It’s a charming town with a nice British feel. We took a taxi back to the hotel.

If you decide to stay in London instead, you will need to feel comfortable with the London transportation system— with cruise luggage.

May I suggest another option? Can you continue directly to Southampton after landing at Heathrow, and stay overnight there prior to the cruise? I have never been to Southampton but I would assume there are hotels and restaurants. Your parents will be tired after the flight. You can wander a bit, they can get a good night’s sleep and be rested for the whole cruise boarding process. I would assume there are trains or buses you could take from Heathrow to Southampton for less than a cruise transfer.

To follow up on Charlene’s post-
National Express Coaches leave from the coach area just outside terminal 5 arrivals (usually around stand 14 or 15 to the left first row) about every two hours for Southampton. A very minimal amount of dealing with luggage as short walk and driver loads it under the coach. At Southampton, just catch a taxi the short distance to hotel. We stayed at Premier Inn West Quay.

Thank you all for such great suggestions. I am going to check into going straight to Southampton. That may be best and easiest option!