Presumably you're currently, legally, known by your married name, so your "old name" is the married name with middle name. And, in any case, you can just change it to whatever you like, so if you don't want to be known by your married name any more, for whatever reason, you could change it to your birth name (or vice versa).
A Deed Poll allows you to change your name to whatever you wish, and have as many changes as you like, as long as they are all at once and as long as you have two witnesses.