The travelodge in Marylebone has £49 savers rooms for Mon26, Tues 27 and Thurs 29, but for Wed 28 there are none available and it it would cost you £90. If you want to book this go to
www.travelodge.co.uk and click on saver rooms logo,, put in Marylebone and you will need to book each of the nights separate to get this rate on the left. Then book the Wed dearer room on it own. If you just put in th block dates it charges you £90 per night for each of the rooms. There are single and twin rooms available for the same rates,-the twin rooms, might give you more room. This is opposite the Marylebone train station and it is 4 stops on the tube to Oxford Street(Oxford Circus stop). That is about 10-15 mins travelling time.
Don't know if this is what you are looking for but found a room rental with shared facilities in nearby St Johns Wood for £35 a night. It says the 139 and 189 buses stops in the road and these buses goes to Oxford street. It would be about 20 mins away on the bus.
http://www.holidaylettings.co.uk/ren...hns-wood/12816
www.easyhotel.com has rooms for £40 a night by Earls court tube station and you only need to change once on the tube to get to Oxford Circus station-Piccadilly line 4 stops to Green park, change to victoria line and 1 stop to Oxford circus. (20 mins travelling).
Before you go to London order an Oyster card for cheaper travel from
www.tfl.gov.uk. It is £3 for the card but works out a lot cheaper for regular journeys at peak times.