(20 Apr 2015, 6:02 pm)northern156 wrote £70/night is too expensive for me to be honest! £50 tops really. I've found some VERY reasonably priced hotels on the outskirts, such as Luton/Bedford/Stevenage etc. with the intention of 'commuting in' as at least one of the days I go will be a weekday. However although the hotel is cheaper, the train fares are astronomical! With an Oyster card I would've got a Zone 1-9 Day Travelcard (I'd be riding around on trains/buses all day) however Zone 9 is a good few miles from the above hotels. Basically the M25 is where the cheap hotels start and the quite cheap travel ends.
As an alternative, you could do down to Brighton on day 1. Spend time traveling about and photograpphing down there, stop over night, and then perhaps in to London for day 2? That way you could still spend plenty of time travelling about and photograpphing, prior to a trip home?
Brighton prices tend to be decent. Last year I was booked into the Jurys Inn (just behind the station), and that wasn't too bad - £60 a night I think? I'd be wary of anyone (other than Travel Lodge etc) providing a room for £50 down south.