Customs in UK

Assuming both flights are part of the same ticket, both Immigration (passport check) and Customs (the stuff you are bringing int the country) will be at the airport in France. At Heathrow you will probably have to go through a security checkpoint.

Thanks. It's actually not the same, we are switching airlines and purchased the tickets separately. I'm trying to decide how much time we will need to catch the connecting flight, there is one I'd like to get just an hour and ten minutes after arrival.

Also landing at Gatwick, and catching connecting flight there.

If you purchased them not as a through ticket - as you said - then you will likely have to check in for the second flight. What time does check in close? If your second flight is on Easyjet or similar you will need longer than you have.

Are both flights in the same terminal?

Short answer - I don't think your plan is a bet that I would make.

Excellent point about check in time. I agree it is too tight of a connection for the earlier flight. Thank you!

I’m with Nigel, it’s doubtful that you can make a 70 minute connection.

Have you already checked Gatwick’s connection page? 60 minutes minimum for same terminal and 90 minutes if you need to change terminals. That’s assuming your arrival is on time.

https://www.gatwickairport.com/at-the-airport/flying-in/flight-connections/

I'd forget anything that close on two tickets - you will need to make the minimum checkin time before the gate time.

Note that if your onward flight is with easyJet then you cannot use the transfer facilities and you must go through UK immigration, according to Gatwick Airport's website.

You can't escape going through security as the CAA doesn't take on trust the competence of other countries' airport security, including the TSA.

Thank you for all the very helpful input! Reading the link, I realized I will need to collect luggage and then recheck it in so you are all right, the 70 minutes to connect will not work. Thank you very much