Hey
medhead, it sounds like a great trip.
If you were to walk from St James to Bayswater it will take about 30 to 45 mins from memory, the quickest route will be around Liz's house (buckingham palace) and across hyde park. A lovely walk to do once or twice but I am not sure how often I would want to do it. If you do walk you will pass the memorial to Princess Diana, a nice water monument that keeps breaking down.
I would say the quickest way to get there would be the tube from St James' Park on the circle line to Notting Hill Gate and then walk from there (about 500m). the tube journey should take about 5-10 mins.
In terms of getting to the airport, I know a lot of people rave about the train from LHR to Paddington but I always used the tube, and again you can get it from St James' Park (District/circle line and then change at South Kensington/Glouster Park onto the Piccadilly Line). It doesnt take that much longer, it is a little bit cheaper, you get a free 'newspaper' and I didnt have to get across London to get to there (I lived in SE London where the tube doesnt exist). With a 9pm flight time I would probably want to be there about 7pm which would mean leaving about 6pm. It will be rush hour so it can be a bit crazy on the tube, although there should be a mass exodus at Victoria the stop after you get on. Be prepared for tutting and muttering if you have luggage.
If you are doing some overground travel transport for london (
Home | Transport for London) has some great maps and are generally happy to help. you can also get some useful, and not so useful alternates, here (
Geofftech - Tube - Silly Tube Maps) I like the realistic and its quicker to walk alternates.
Now things to do in London.
Over the weekend there are loads of tourists but I guess that is not going to be a problem for you.
I actually used to work in the Notting Hill/Baywater areas so they hold a very fond place in my memory. Saturdays are generally market days. My personal favourites are the Portobello Road market, it is just like the film, and in fact if you watch it before you go you will probably see some of the stall holders still working away. You can also go into the bookshop that the one in the film is based on. There is lots of tat but the colour and vibrancy of the place is amazing. Its about 1km long and runs pretty much the whole length of Portobello Road, from Notting Hill Gate down to Westbourne Park Grove. If you like coffee there is a great place on Portobello Rd that roasts its own beans (daily I believe) and will grind them for you. You can also sit in and watch the world go by with a great coffee and pastry.
If food is more of your thing then Borough Market near London Bridge Station is a must. they have stalls selling all kinds of edible delights. From general fruit and veg (from the growers) to pies, cured meats, cheeses (from Neals Cheese Yard), sandwiches. Friends of mine used to actually do their regular food shopping there so the prices are pretty reasonable.
The Globe is a great place to go and really quite cheap if you get a yardling ticket, GBP5 when I was there. The legs do begin to ache after a while and you are exposed to the elements which means you will get wet (no umberellas allowed and it is England).
If I can be so bold as to suggest a bit of an intinery for Saturday.
early doors ish get to Portobello Road, have a bit of breakky, from one of the many, many stalls.
Walk through the market to Westbourne Park Road, take a left and then left agin and walk to Ladbroke Grove station. Tube to Baker Street and change onto the Jubilee line to London Bridge.
Out of the station and into Borough Market for a look around and a feed. Steak sandwich and a pint, or a full cooked and a Guiness (the market porter pub is famously open early for the market worker as they will have been there is o'dark hundred,
The Market Porter | Famous Public House in London's Borough Market | Market Taverns Ltd).
When you have finished there walk west along the river (the river is on your left) past the Globe (pick up your tickets) and then on to the Tate Modern.
A bit of a look around there and then across to St Pauls for a bit.
Back across the footbrigde to the Southbank and into the Globe for the show.
Post show meal and drinks at either the pubs along the southbank (or a pizza express next to the Globe).
Not a bad day if I do say so...
If it is beer that you want they I cannot recomment these website enough
BITE # pubs and bars - beerintheevening.com and
Pub guide to London pubs and other pubs in the UK. | Fancyapint?. These websites were invaluable when I lived in London. Here is the link to the ones around Notting Hill
Find pub guide for notting hill. Read pub reviews in Fancyapint anything that has a 4+ pint rating is worth going to.
A few last words of advice, in additon to the usual passport/credit card/cash stuff.
1) stand on the right hand side of the escalators,
2) when you get off the escalator move away, do not stop and look around you,
3) don't talk to people on the bus/tube,
4) stand on the right hand side of the escalators,
5) don't just stop when walking down the street,
6) try the local beer, and I don't mean fizzy cr*p, both Fullers and Youngs are local brewers (large scale) and will have some tasty ales on offer (they will be flat and a little bit warmer that lager/pils but for my money are vastly better, there will also be some even smaller brewers and better beers available if you are a little bit adventurous. Normally of you ask to try a little bit they will allow you to, and lastly
7) stand on the right hand side of the escalators.
Oh yeah, have fun