Although Copyright's reply is correct as far as it goes, the actual sentence that is the thread header does not make sense, and might include an error of word usage.
• You may not use "send" as a synonym of "go" or "travel." If you mean, "My parents allow me to go with you to London" or "My parents allow me to travel with you to London," then you can't substitute "send."
• "Send" requires a direct object. You could say, "My parents allow me to send a gift for Frank with you to London." That means that your parents are letting you give the person you are addressing a gift for Frank, that the person you are addressing will take to London (where Frank is).
• You could also say, "My parents are sending me with you to London." That would mean that your parents are directing or ordering you to go to London with "you" or that for the purpose and length of the trip they are entrusting you to the care and supervision of "you."
In the header sentence, "my" and "london" should be capitalized, "my" because it begins the sentence and "London" because it is a proper noun—the name of a specific person or place. The sentence also should have a period at the end. Correct capitalization and punctuation are required by the forum rules that Copyright referred you to.