Disembarking in Portsmouth, how much time to make LHR flight?

I will be disembarking Ponant L'Austral in Portsmouth at 8am. I am thinking of taking a private car to LHR, I will also be checking in Business Class. I am looking at a 12pm flight, will I have adequate time or need to take later flight?

Thanks for your advice

I wouldn't like to be leaving it that tight. Is it an international flight? If so you would normally need to be checked in around 3 hours prior.

Yes, it is an international flight

I would be allowing at least 2 hours of drive time from Portsmouth to Heathrow. I would be taking a later flight ( more like 3pm, less stress and if you are going business you have the lounge at the airport to relax in once at the airport.

Thank you for the info, very helpful since I was considering the early flights. Will take your advice for a less stressful day and enjoy the lounge

A long-haul noon flight is possible on a Saturday or Sunday, but even then you,d have little wiggle-room.

A later flight - after about 2pm would be sensible.

JB :)