Ranjan, you claiming that ur wife has a mental disorder does not mean that she cannot work /earn ......period ! There are several celebrities and even successful businessman who have openly admitted suffering from mental illness but are doing very well professionally.
Right now the case is at the interim stage and the court will not look at basis to approve/disapprove that ur wife is a mental case.
If ur wife has a mental disorder then how did she complete MBA ?? ur stand in the court at this stage should be that ur wife's behaviour was irrational / irratic bcos of which it was becoming impossible to live a peaceful life with her. You may say that she may have faked to u that she is a mental patient OR by exhibiting behaviour of a mentally retarded person inorder to trouble/harass you with malifide intention so that u leave her and she can claim hefty alimony.. Whether ur wife is really suffering from mental disorder will be decided at evidence stage.
If u have not provided any documents to prove ur low income then its unlikely that maintenance will be reduced at HC unless u turn the tables and prove that ur wife is capable to earn and highly qualified. Did she have any work exp prior to marriage ??
Secondly you give a proposal to court to pay her maintenance for 6 months and support her to find a job for herself OR you arrange a job for her. Once she finds job then u stop paying maintenance to her. Game over !
Regarding standard of living issues between london and India u need to hire an expert lawyer who has handled similar cases, there are various factors to be considered and many local lawyers goof up dealing with this critical issue. let me know from which city you are so that i can suggest lawyer who can help you