Hey there Nikhil,
Great to hear from you!
Let me start by jumping straight into your questions:

1. Is career change possible after 9 years in IT?

A career change is always possible, but frankly a career change into finance at this later stage and age will be likely very difficult. I don't want to dissuade you from wanting or trying, but the realities are that employers will have a plethora of choice from younger talent with experience in finance, and they have little reason to take an older IT guy. Where it can work, is if you make the right contacts and cultivate them, and then if you perform well in your MBA internship, you could land that job too. But you may want to consider other options - product management, or general management in IT or other things that excite you, but which will be easier to attain.

1. If possible, want to know the schools to target if I wish to change career from IT to finance.

Any school with good placements in Finance, so yes LBS, Oxbridge, etc.

2. Said b-school offers high placements for Finance guys. Still is doing MBA from UK post Brexit makes sense ?

Here I can't answer you at all. I'm no prophet! Actually nobody really knows that will happen with the Brexit, so a mystery to me too. But still, there will always be the London financial district.

3. Will my more experience (10 while starting MBA) & age(33) hold me back ?

If you apply to European (continental) B-schools or EMBAs not necessarily. But it will make your desired career change difficult.

So overall, I think B-school can be a very interesting investment for you, but please do realize that your desired switch to Finance may be quite challenging, so consider other options as well.

Best,
JF