Trying to make a proper regular expression
 

Good day,

Can somebody help me please to set up this? -- To check if there's one or up to 3 words with "A-Z" & "a-z" expressions in the custom field excluding the sentences like "www", "http", ":" and "//", along with the regular numbers. What I particularly need is to have a custom profile field that allows all of the English letters, no special characters and no web-like stuff mentioned above. If you're unaware of the exact string, anything that's blocking the numbers, "www" & "http://" will do.

Thank you.