Configure Custom Actions I only ever want an action to be performed on one single record

Am using functions and custom actions (In the header section of a view ) successfully

Question

For my view if i use "Execute action for collection of records" or "Execute action for each record" the user can click multiple records.

In my case (booking rooms) i only want them to be able to book one room at a time so i

a) Only want one record to be selected
or
b) Know if multiple records have been selected so i can check for it

Any suggestions

thanks