Always worth checking the Pinformer website.
Wardour street is a easy distance to you - The Las Vegas "Casino" has three pins in it normally.
The pipeline is also easy to get to and has 6 or so machines.
Not been to the place in Chiswick yet but it's a fair trek from the Strand
Don't bother with the MM in Waterloo as it's shagged. Might be a machine in Big Red in Archway or one in the hope & Anchor in Highbury & Islington
You would also be welcome to come here on Thursday evening if you fancy it. (sorry it's so specific but I need to time it for when my other half is out) Got 15 pins set up at the moment - 10 mins from London Bridge