If your call is OTM at expiration, it will be worthless and it will expire.
If your call is ITM at expiration, it will have some intrinsic value.
If an option is one cent or more in-the-money (ITM) at expiration, the Option Clearing Corp (OCC) will automatically exercise options whether they are long or short. This is called Exercise by Exception. For equity options, you will end up with a long or short position in the underlying (index options are cash settled). If you are long the option, you can designate to the OCC via your broker that it is not auto exercised at expiration. This would make sense if the option is ITM by pennies and your commission and/or fees to close the position exceeds the ITM amount.
If your call is exercised at expiration and you don't have enough money to covered assignment, you have incurred a freeriding violation and your account will be restricted. Some brokers will automatically close such options just before the close on the day of expiration.
It is always better to sell a long option if it has remaining time premium. The exception to this would be if an ITM option trades below its intrinsic value (and you have the funds available to handle the exercise). Read my answer here.
or let the broker do it for you
What do you mean by that?