My wife and I have an overnight layover at LHR. There's a Hilton inside terminal four. We are arriving and departing from terminal 5. I know that they are at opposite ends of the airport, but will it be quicker and easier to stay inside rather than leave and come back through security and passport check? How long will it take to get from T4 to T5?
Do you know there is a hotel at Terminal 5, the Sofitel? http://www.sofitel.com/gb/hotel-6214-sofitel-london-heathrow/index.shtml
You have to go through immigration to get to any hotel, so it makes more sense to stay at the Sofitel. Unless, of course, you can get a better rate at the Hilton.
Check your options for travel between the terminals here: http://www.heathrowairport.com/heathrow-airport-guide/travel-between-terminals#table
What time do you arrive and depart?
We arrive at 9:30pm and depart at 09:30am.
If one has to go through immigration does that alsomean security?
Immigration to get into the country; security to get on to your plane. You will have to fill out a landing card which a flight attendant should hand to you on board before you arrive in London.
Sofitel will be easiest.
If you want something cheaper, the hoppa bus will still be running when you arrive so you can easily choose any hotel on that route.
I stayed at the Premier Inn Terminal 5, which is a four minute free public bus ride from Terminal 5, on Bath Rd. (It will take you just about as long to get to T5 from T4.) Clean, comfortable and inexpensive. You will do passport check when you arrive at Heathrow at night, and security in the morning to get to your plane.
See this page on the London Toolkit site for detailed information on the Premier Inn Terminal 5, including how to get there on city bus 423 (free ride).
We stayed at the Yotel Hotel inside Terminal 4. What a hoot. It's like being in a ships cabin (size wise). In the morning, we took the train to Terminal 1 for our flight home to the USA.