Critique my London itinerary, please?!

Here are my thoughts...
London Wednesday...where will you put your luggage while you visit the British Library? You can easily see the public room in an hour or less if you don't read everything. Hit the highlights and then check in to your apartment.
The Tate can really take as little or as much time as you like. We spent almost two full days there last summer but you can just go to a few rooms...maybe see the Rothkos and one other section. There are 4 (I think?) floors with 3 or 4 sections each. Some sections are free, some of the special exhibitions require a ticket. The gift shop is one of the better ones around if you are into modernism.
I'm assuming you just want to see the Houses of Parliament and then ride the Eye at night. It'll be a lot to do but you certainly can if you just want a quick overview.
Thursday is perfect.
Friday...this is a lot for one day. So much walking! Again, you can spend as much or as little time as you like in each of these but you will have to get a move on. All of these places are pretty extensive - you may have to wait in line for parts of the Tower (especially the crown jewels). If you don't go to the roof of St. Pauls you can take a quick spin through the church and the undercroft in 45 minutes. Harrod's is also massive...choose the departments you want to see. The food halls are worth it as are the jewelry/watch rooms, the "Millionaire's" shop, the pet shop, and the toy shop. The "Spirit of Quatar" is very interesting too - have coffee in the attached coffee salon. But maybe you are interested in other things? Hyde and Kensington are HUGE parks so target what you want to see. V & A again has so many parts to it...target what you want to see and don't try to see too much.
Saturday...Portobello get VERY crowded on the weekend. Definitely get there as early as you can. BP Guards takes just a few minutes. Westminster will have a line to get in. You really need to do an audio tour or guided tour to get the most out of it. Not much is labeled and you won't know what you are looking at otherwise. Ah, the Tate Modern again...good call!
Sunday...doable but busy!
You are packing a lot in but you can do it if you get an early start - to make meals easier I would have lunch in the undercroft of St. Paul's on Friday. The Tate has a great little self-service cafe with an AMAZING view over St. Paul's and the Thames. Eat at Portobello Road - lots of great food vendors set up on the lower part of the road.

Exciting, good for you traveling so soon and to such wonderful destinations. I'm officially jealous. As for the London itinerary, as others have suggested, it is a lot to try to fit in. Do not underestimate the time it takes to get from one location to the next, even within London. For example, Tower of London (which I could easily spend 4 hours in) to St. Pauls is close (walk or tube), but then Harrods and Hyde Park are a bit of a haul from either place. You'll lose time in transit. If you did Tower of London, St. Pauls, Hyde Park, and the V&A, that alone is a very full day. In any case, enjoy the trip!

Agree with others you definitely need to factor in travel time to and from the apartment in Barnet, a minimum of 30-45 minutes each way. Personally, I'd get settled in the apartment first. Having no luggage to worry about will be of benefit and you can then stay out as long as you wish. Will also allow you to see what's nearby in your neighborhood so you aren't searching for a place to grocery shop the next morning. Once you are settled take the Piccadilly Line to Green Park station, get off and change to a Victoria train to Westminster. Exit at Westminster and you are at the House of Parliament with the London eye across the Thames. Depending on your stamina you can then take the tube or walk to the Tate Britian. London is lovely after the sun sets so why not take the tube to Leicester Square and then stroll over to have dinner somewhere in Covent Garden. Or take the tube to Knightsbridge and visit Harrod's. From there home for a good night's rest. Friday you are jumping around a bit so Google Tower of London, United Kingdom on the satellite option and start to plot what's close to what to save you time. You'll see Harrod's isn't that close to anything and thus my reason for seeing it the first night. Simply saying take a bit more time to see how close locations are and plan to see those on the same day. You chosen two fabulous cities to explore. Have a great trip!!!

Hi All,

Thank you very much for your detailed answers! Putting together an itinerary is like putting together a monster of a puzzle!

My thoughts on crazy-Wednesday - I've read that the library has lockers and can accommodate luggage for a one pound deposit (much cheaper than left-luggage at Kings Cross or St. Pancras). If we can't get a locker right away I think we'll just head straight to the apartment. We don't want the owner to wait too late to check us in. We are staying near the Totteridge and Whetstone station; Google says around 40-50 minutes to London, depending on where.

I forgot to mention possibly doing the British Museum early on Thursday. Though it's out of the way - would it make more sense to toss Abbey Road in there too? Then we could maybe shift something for Sunday morning. I'm also 100% okay to cut Greenwich/Docklands out too.

We've tried to save all of the "open late" options for in the evening so we can make the most out of our days. I should mention we'll be doing the Zones 1-4 7-day travel card so we can jump on the Tube or Bus at any time.

Thank you again for any help!

I agree with PPs that Friday is too packed with stuff on opposite ends of the city. If you feel like you have to pack it all in, do the Tower in the morning, take the Tube to hit up Harrods around lunchtime, then stroll through Hyde Park and end up at the Victoria & Albert Museum. Save Kensington for another trip (or day if you have to cram it in.) When my itinerary got crowded St. Paul's fell off the list quickly because Westminster Abbey was the main attraction for me and St. Paul's is a bit out of the way. Everything else looks pretty doable.

If you go to Harrod's, they offer a great buffet lunch in their "Georgian Room" upstairs. It is offered until 3:30 PM daily. It is delicious food in a beautiful setting.