Overnight Layover @ Heathrow

Stay at Heathrow and get a good night’s sleep.

You'll need to use transit from T3 to T4. An alternative to going into London would be heading to Windsor/Eton. They are quite close to Heathrow. There is bus service, though I don't know how frequent it is. Maybe a taxi wouldn't break the bank? I haven't been there yet, but I'm going to try to make it happen the next time I go to London--not after flying overnight, though; that wouldn't work for me.

Richmond is a lovely little town. Stroll around Richmond along the Thames. Stop for food or drinks at White Cross. Richmond Park is so interesting, and has a long royal history. Great walk, fresh air, amazing wildlife. Or Royal Botanic Garden, Kews. Not far from Heathrow, and a terrific suburb of London.

I'm sure there's a bus or taxi or an easy enough way to get there from Heathrow. A nice way to spend an afternoon, before returning to your hotel at Heathrow for the night.

You can't walk from T3 to T4. You have to use transit.

If you have US or Canadian passports you should be able to use the egates for immigration and bypass talking to anyone.

I would think that around 60 minutes after touchdown you should be at the hotel. However, that early, your room will probably not be ready. Ask the hotel to store your bags until you return from your outing. London is one hour by public transit depending on where you want to go.

T4 is several miles from T3. Use the free connections... it is easy, fast - and free

Arriving at 10am you can have your bags dropped off and be in central London probably by 1pm at the latest, with the rest of the day to explore. Windsor would have been a good alternative but if you've already been there I would choose another attraction that interests you and build half a day around that. You don't need to head back to Heathrow until at least 10pm.

The Tower of London seems to be the obvious big attraction missing from what you have already seen but there are ,odds of others - St Pauls, British Museum, National Gallery and National Portrait Gallery, Tate Britain and Tate Modern, The V&A, Science and Natural History Museums etc etc.

Rer- KD above- to get to Richmond take the Piccadily line tube to Turnham Green, and change there onto the District Line to Richmond.

The other easy way to do it is a 25 minute ride on Bus 285 from Heathrow Central Bus Station (Terminal 2/3) to Feltham Station, then a 10 minute journey on South Western Trains to Richmond. The train runs every 15 minutes or less.

when looking for the trains to Richmond you will be looking South Western Railway (SWR, logo is a fanciful blue arrow pointing up and to the right). There have been so many franchise and name changes they get confusing. The previous incarnation was South West Trains.

with Feltham Prison and Young Offender Institution I might only consider the bus to Feltham in the day. I know that it used to be the way before the Piccadilly Line was extended, but that's been some time and I have had some interesting times driving through that area. I'm sure all the people are lovely but ...