Afternoon and Evening in London

The Piccadilly Line will take you to South Kensington, Knightsbridge, Hyde Park Corner, Piccadilly Circus, Leicester Square, and Covent Gardens. Any of those, with the exception of Hyde Park Corner, would offer shops and restaurants in good variety. Knightsbridge is very close to Hyde Park and if it is still daytime you could have a nice walk around there, then find someplace for dinner. I see lots of shops and restaurants along Brampton Road and Knightsbridge (on Google maps).

Covent Garden could be fun as well.

Hopefully someone will have more specific recommendations.

Lola has given some good suggestions- Covent Garden would be my top pick, with Covent Garden Market itself, plus many lovely small shops. In terms of eating, I would recommend one of London's numerous pubs as a nice option. Another favourite of mine is The Ivy, a nice and fairly upmarket eatery. It's part of a chain, but don't let that put you off. Alternatively there's also Dean Street Townhouse if you want something trendier.

Another option (a couple of stops on the tube or walking from Covent Garden) is to get off at Piccadilly Circus and walk up Piccadilly and Regent Street, where there are lots of big and very smart shops. Coming off Picccadilly is Burlington Arcade and Bond Street (luxury brands). Two department stores I'd recommend - Fortnum and Mason (Picccadilly) and Liberty (Regent St). Nearby Soho has plenty of places to eat. I can also recommend the Great British Restaurant in Brown's hotel.

Parks - you're near Green Park and St James's Park (daylight permitting - very limited lighting in parks at night).
Historic sites - depending on how much time you have, you can walk to St James's Palace, Buckingham Palace, Westminster Abbey, Downing St. Obviously bear in mind it gets dark early in winter.

Thank you both! Great ideas and Covent Gardens sounds like good, easy option.

If it were me I’d pay for a HEX ( Heathrow Express)
at least 2 months before. From Terminal 5 use the HEX and take the 15 minute ride to Paddington. At Paddington f take an underground train to Westminster station. Use a tap credit or debit card to for the Tube. Once at Westminster station, get off. Signage provides the correct exit to Parliament, West Minister Abbey.

Walk around Parliament Square then walk up Whitehall to Trafalgar Square and from there into Convent Garden. Or take Birdcage Walk adjacent to St James Park up to Buckingham Palace.

Plenty of food options near Covent Garden.

Thank you. I will look into Hex.

The Piccadilly line must have been re routed if it has started stopping at Paddington and at Westminster.
By the time you have potentially waited for a HEX, which is far less frequent than the Piccadilly from Heathrow then changed to the tube at Paddington any time savings offered by the HEX have potentially vanished.
Not the best route to Westminster.

Unless the route has changed in the past 2 years HEX arrives at Paddington in 15-20 minutes from LHR.

Rode it in 2022. Got out at Paddington and took a 15 minute stroll to my accommodation across the road from Lancaster Gate and the Italian Gardens.

SAME route I’ve taken for years.

Can’t comment on the Elizabeth Line from Heathrow as I’ve not ridden it for that route.

My only Elizabeth Line trip was from Ealing Broadway to Farringdon.

Admit Piccadilly won’t get you to Westminster but Circle Line does without a change.

Claudia, Stuart is simply pointing out that the Piccadilly Line Does not call at Paddington.

If one takes the Heathrow Express to Paddington, then it would be the District or Circle line, not Piccadilly, to get to Westminster. .Maybe just a typo on your part.

Also, the Heathrow Express is no longer offering the cheap £5.50 tickets. The cheaper set same-day return is £30.

If the OP hasn't been to London before then maybe, subjectively, the Picc/District route with the well known cross platform change (rather than crossing Paddington station) may be the easier- a matter of opinion and preference ultimately.

Just a comment- I was at Heathrow Central about three weeks ago mid-afternoon on a day of service disruption on both HEX and Elizabeth Line (one of many such days recently). And the platform was simply dis-organised overcrowded chaos. When a HEX did come in it had a heavily extended dwell time with folk jumping on and off in confusion as to which train it was and much yelling from over-stressed platform staff. Given that both services (HEX and Elizabeth) in a way are premium products it just felt awful to me, and I know what I am doing. Welcome (not) to Britain. Then 3 hours or so later when I came back from Ealing Broadway at nearly 7pm the Elizabeth Line was so packed Heathrow bound (that far out) I struggled to get on the train at all (again due to a thinned out service).
Boy I needed the relaxation of my near 2 hour bus ride from Heathrow afterwards. In between I'd had service issues on the Central line as well, three missing London buses in succession, then a bus breakdown!!- all on the same route. Not TfL's finest late afternoon.

When you exit customs at T5, turn right and walk to the end of the hall. Along the way you'll pass the entrance to the HEX/Elizabeth Line, then the Underground (Piccadilly Line) and finally the exit for the car park (parking garage) and the Sofitel. (It's directly across from an M & S Simply Food that's a small market. It has lots of prepared foods and is open 24 hours.)

You take the elevator up (one or two flights, forget) and its then down a long enclosed hallway to the Sofitel. (I've stayed numerous times and it's nice.)

So, the trains and underground are very close to the hotel.

Along the Piccadilly line, you have South Kensington (museum row), Knightsbridge (Harrods), Hyde Park Corner (Hyde Park), Green Park (Buckingham Palace, Ritz Hotel, Fortnum & Mason), Piccadilly Circus (the Times Square of London), Leicester Square (theatre), and Covent Garden (shops, markets). If you want to go to see Big Ben, Parliament and Westminster Abbey, take the Piccadilly line to Hammersmith. Get off, cross the platform (about 12 feet) and get a District Line train to Westminster.

My top choices for a full time tourist is Westminster, Covent Garden and Piccadilly Circus. (It's only about a 10 minute walk from Covent Garden to Piccadilly Circus.)

My suggestion....go to Westminster area see Parliament, Big Ben and Westminster Abbey,=. After working hours, the area is quiet. Then either walk (about 20 minutes) or take a bus or London taxi to Covent Garden. Lots of restaurants, pubs, etc. After dinner, just hop on the Piccadilly line at Covent Garden and it takes you directly back to Heathrow T5 in just under an hour. (Make sure the Piccadilly line train says "Terminal 2,3 and 5." Not all Piccadilly line trains go to T5.)

Taking the HEX and then transferring to the tube will save no more than 15 minutes and cost a lot more than the tube. A lot more.) People forget the walking time between Paddington Station and Paddington Underground as well as waiting for the tube train to arrive.

You are the best! This is exactly what I needed to know. Thank you so much. I will cut and paste this into my travel folder.