Our family of 9 (5 adults and 4 children) are flying into LHR at eleven in the morning on July 29. We need to get to our hotel in Windsor. What is the easiest, most efficient and affordable way to get there? The next day we need to get to Southampton to the cruise ship. Any suggestions on how to get there also?
Many will disagree, and that's perfectly ok. But the fact is that quite often the easiest, most efficient, and affordable ways are somewhat mutually exclusive. The most cost effective will probably not be easy or efficient. The easiest will probably not be the least expensive. In your particular situation you might want to check into a private van car service. After a long flight, some jet lag, not being familiar with the area, and having four children along, there will be nothing better than having your private driver meet you inside the terminal and whisk you to your hotel in Windsor and to the port the next day. No worry about trying to find a cab or cabs, trying to figure out the train logistics, or just having a "lost" feeling. It is not the cheapest way, but it is, in my opinion, definitely the best. After all, this is supposed to be a vacation -- not an obstacle course. Do some serious research by googling "van services from Heathrow". Comparing their prices to the total price of all the train tickets might be surprising.
The bus from Heathrow into Windsor would be the most affordable. Then to get to Southampton take the train from Windsor Windsor &Eton Central, which is beside the Ye Harte & Garter Hotel, you will have to change in Slough and again in Reading. Slough is only eight miles from Windsor, so you could take a cab to the Slough train station, then you would only change in Reading.
"Do some serious research by googling "van services from Heathrow"."
Just to avoid confusion, a "van" in the UK is for carrying goods (no windows):
https://upload.wikimedia.org/wikipedia/commons/9/96/UK_Mail_van.JPG
What you would need for 9 people is a minibus:
Keep an eye on the fare to Southampton from Eton and Windsor Riverside station via London Waterloo or Clapham Junction. The journey time is much the same, only one change and it is at the moment only £13 on a promotional fare. Currently this is only available to 14 July, it may get extended.
A private hire of a minibus might still work out cheaper for your numbers though.
OOPS -- Just plain forgot the difference between a van and mini bus. Guess I've been back in the states way too long.
We just returned from a trip to the UK earlier this month. We landed at Heathrow and spent our first night in Windsor. I looked at several car services and settled on Windsor Car Service as it was local and had reviewed decently on TA. We had a six passenger car/van so it was smaller than what you'll need but the cost was either 30 or 33 GBP for the trip from LHR to our hotel in Windsor. Their driver was waiting for us just outside of baggage claim in terminal 2 and there were no problems. They would probably take you to Southampton also.