best way from LHR to Southhampton cruise line
 

My husband and I are going on a 12 days British Isle princess cruise line round trip from Southampton in August 2018. Please help to find the best way from LHR to Southampton, via train or bus? We have one check-in suitcase and two carry-on bags. Thank you.

The best way is likely the transfer usually offered though the Cruise line but they are usually quite pricey and generally only work if you booked your flights through them..

There is no train from LHR to Southampton and any connection by public transport would buses and trains or crossing most of London to Waterloo station and train from there.

Cheapest is a National Express Coach https://www.nationalexpress.com/en/a...on-to-heathrow

A pre-booked car service like one of these would be easy, pricier than the coach but usually cheaper than a cruise transfer..
Taxi From Heathrow To Southampton ? Heathrow Taxi To Southampton Cruise Terminal, Transport From Heathrow To Southampton, Airport Transfers To Southampton Taxi

Express Airport Transport | Taxis for All London Airports, UK Cruise Ports and Train/Tube Stations, To & From Anywhere in the UK

UK Airport Transfers Taxi TO & FROM Heathrow, Gatwick, Stansted, Luton and London City Airport

janisj is absolutely correct, and your interpretation of "Best" is very much up to your judgement based on convenience and cost.
When you mention round trip from Southampton, are you going straight back after the cruise arrives back in Southampton? If so, there are slight advantages to arranging a return at the same time in some cases.
For example - a one off taxi fare (pre booked) will cost somewhere between £80 and £110 from Heathrow - but if you use a smaller taxi firm, and arrange a return at the same time, some will give you a cheaper rate (£150 return)
If you use the Rail-air bus from LHR to Reading station (every 20 minutes), the individual fare is £16, but the return is only £17. (If you book in advance, train fares from Reading to Southampton can be around £12)

I probably do this journey at least a couple of times a year - and my preference is the National Express Bus. If you prebook, the fares can be as low as £12, but I add the £5 airport option which allows me to get any bus up to 12 hours before or after the designated coach (useful if theplane is delayed). The downside to this is that the buses only go about every 2 hours, so if you are unlucky with timing, you may have a longish wait at the airport.

Thank you Janisj and willit for your replies. Is the National Express Bus available directly from LHR to Southampton?

Did you check the link I provided up thread? . . . >>Cheapest is a National Express Coach https://www.nationalexpress.com/en/a...on-to-heathrow <<

Yes, there is one every 2 hours from about 6am.
The bus stops at the NE bus station in the centre of the city. The Docks are walkable, but it would be more sensible to take a taxi which shouldn't cost any more than £10 (and will probably be less).

Thanks again Janisj and willit. I got it.