We are travelling to London and require accomodation in London from 20th August until the 6 th September and would like places that would suit -we are on a budget - self contained units would be ideal for that length of time but any suggestions would be appreciated. My husband and I will be there for the whole time and we are being joined by another couple on the 31 st August so they could have their own accomodation or share with us.

"<i>we are on a budget</i>"

Well, most everybody travels on a budget of some sort. The problem is -- we don't know what yours is . . .

How much do you want to spend?

About sixty or seventy pound a night per room.

That's a very low budget for London - barely enough for a modest twin in a 2-star hotel in areas like Paddington. There is no way you can get a self-catering unit sleeping 4 (two bedrooms) for that price. Also you are coming in peak period.
Try some motel chains like Travelodge and Premier Inn, they sometimes have cheaper rooms booked in advance (no cancellation or change alowed), though I doubt a lot of availabilty for that busy period.

Alec is generally correct. But by pooling both couples money - you'd have £120-£140 a night which would get you a nice 1 bdrm + sofabed, or a satisfactory 2 bedroom flat.

But -- that only helps for the last week. Your budget isn't enough to get much of a studio or 1 bdrm from the 20th-31st.

And even Priceline isn't that good an option for you -- PL will regularly get very nice 4 star hotels for around £60-£70 a night. But it is hard to get long bookings so you'd have to make multiple bids and possibly have to move hotel several times.

Check out http://www.lsevacations.co.uk/ and http://www.lsetopfloor.co.uk/