In options can i buy any number of lots(quantitiy) or do i have any limit as an individual trader in terms of lots or total amount

You can read all about position limits here -

Yes you can buy many number of lots and accumulate. (For retail trader)

In single order you can buy only upto the limit of quantity freeze.

But if you place orders one by one and accumulate the options you can do so until the exchange stipulated limit, which is very very high (for a retail trader)

Exchange specified limit

5% of the open interest in F&O (options and futures combined actually) in the same underlying stock/index (in terms of number of shares/units)

Say for example the total open interest of TCS October 14 expiry is 46,75,625.

You can buy and hold around 2,33,000 option shares of TCS.

Lets Say on may 24th, the bank nifty options of 23000 strike was trading at 50 paise, can i buy 20 lakh shares, i dont know what the total OI on banknifty, is, and does each strike price have a different limit on how much we can buy