I've been in London twice when tube strikes have been on and never found it had much of an effect - I'm always near a mainline station and most people just get the bus (as I normally do myself anyway, because I'm tight and I like my phone to work whilst I'm travelling ).

If I was further out and the Underground was the only practical way of getting to me I'd maybe think twice, but if you don't want to cancel all I'd say is to make sure punters allow for it taking a bit longer to travel and maybe update yourself on which buses stop nearby .

Speaking from a londoner point of view - I had 3 cancellations last week (on the 1st day of the strike: 2x 2hr bookings, and a 1hour booking ) pre booked by regulars, and no phonecalls on the second day of the strike whatsoever, and given it was a Thursday- my busiest day in normal circumstances- So yes, i can say definitely my earnings were affected by the strike.
I guess, if you are by a major train station, you should be fine in theory, and even get some extra people who are just killing the time waiting for a train/traffic to ease etc. But if I was you I wouldn't risk it. Also, it's really unpredictable how long a journey is going to take when all you have is buses you can't get on, and taxis that are not moving anywhere! I got stuck in traffic on Wednesday around Paddington area, and it took around 40 mins to move 200yards (!)

Anyway for me this week is soooooo bad even without a tube strikes i thinking to get few days off and back to work next Monday because i have no more patience