Create Functional Dropdown Menu To Update Expiry Dates?

I am creating a very simple spreadsheet to manage my gym memberships. It basically has membership number, first name, last name, membership type (drop down box) start date and expiry date. I have put in conditional formatting so that the expiry date goes red when expired but i want to try and automate the inputting of the dates so for example.

If i select '1 week membership) from the drop down box in the membership type box it will firstly change the start date to the current date (i think this is using the NOW() function) and secodnly changes the expriry date to todays date plus 6 days. Ofcourse i want the expiry date to increase depending on the selection so if i select 1 month membership it would be now date plus 28 days.

I am stuck as to how i can do this and from internet tutorials have been told it requires macro as it cant be done any other way?