Hi Vinod,
AS per the current trend (on this forum), applicants are getting their visa's within a year (average times)....so you are within the time frame to receive your visa by Feb 2012 (if everything is ok).
Just for your information, if you decide to move back to India, you will not be able to change your VO from London to India. That is absolutely not possible. You will definitely have to inform your VO about the change of address but request for change of VO will not be entertained.
Transfer of file from one VO to another is done only under the circumstance and benefit of "System Integrity" wherein if VO wants certain aspects of the file to be investigated at the local VO of the applicant.
Before you make the move from London to India, be aware that you will not be able to mail your passports to London VO for stamping as it is illegal to send PP outside India. You may either have to go to London in person or use the good help of a friend/family member to carry your passport with an authorization letter.
Mitali
NB: After having read Candestin's post below (#42538), I would like to add that VO WILL NOT MAIL THE PP's OUTSIDE THE COUNTRY, IN THIS CASE LONDON. VO will need an address in London to mail out the PPs.