Hi there! We have a 6 hour layover in London after a 10 hour flight before continuing on to Lisbon. I need a bit of help with logistics in LHR and hopefully someone here can help me.

We want to take advantage of the Lounge at Heathrow that now has sleeping rooms available. Trouble is, the lounge is within the secure area of Terminal 3. We arrive at Term 3 and leave from Term 3, but the flights are not connected. The overnight flight is a one way reward flight on BA, and the second flight (to Lisbon) is a purchased BA ticket, with a return.

So, my question: When we disembark from our overnight flight, will we have to go through customs and immigration, pick up our luggage, leave the secure area? In that case, will it be possible to recheck our luggage that early for our flight to Lisbon so we can get through security to access the Lounge? There is only one lounge I can find that has sleeping rooms that are available to us. And leaving the airport is rather out of the question- not enough time.

If we carry on our luggage would we be able to stay inside the secure area after going through immigration?

I've never had a situation like this before, as our trips are usually longer, and we stay overnight at the arrival city, but not this time.

I do believe if you are same terminal with carry on then you do not have to do immigration or security. If you had to change terminals with carry on then just security. We were in a similar situation last May but we changed terminals and just had to go through security.

(1) You should be able to check your bag all the way through when you check-in for your London flight. Make sure the agent who checks you in sees both BA reservations and puts LIS on the luggage tag. Of course, check in for both flights online the day before so you have both sets of boarding passes.

(2) You will be able to stay airside in Terminal 3. Just act like any other connecting passenger at LHR, you'll have to go through security, but it all happens airside.

Enjoy the lounge!

Are both flights on the same ticket? (I assume not since one is a reward flight. ) If they are on the same ticket, they will check through. If not you may not be able to check bags all the way through. (We always ask when we first check in and sometimes they allow it and other times they do not. This is when flying BA. YMMV with other airlines.)

If you don't get to check bags through, you'll go through immigration, collect your checked bags, and go back to the bag drop desk at departures. I shouldn't think you'd need to worry about not being able to re-check your bags due to the fact that you are laying over -- my sister and Bil dropped their bags for a long layover with no problem at LHR last year. If you want more concrete advice ask on the pertinent forum on Flyer Talk. They are a fabulous resource. If you travel hand baggage only, you're good to go since you would stay airside.

Have a great trip!

Yes -- BA can be a bee-atch about bags. You'd think they'd check them through . . . and they will . . . sometimes. Traveling carry-on only solves that problem.

The BA carry on allowance is the same for long haul and short haul:

"1 handbag/laptop bag (max. 23kg / 51lb and up to 40 x 30 x 15cm / 16 x 12 x 6in)

plus

1 additional cabin bag (max. 23kg / 51lb and up to 56 x 45 x 25cm / 22 x 18 x 10in)"

Thanks for the update as it will help others.
Ughh. I don't even like "wet room" bathrooms. When I'm done with the shower, I want to be done with "wet" and step into a well ventilated, dry environment. I get that it's not a hotel room but sounds like a very bad design.

Curious as to the cost of the sleeping room in the lounge?

This is great to know, thanks!