In England, celebrants cannot legally marry couples but it is still possible to have the ceremony of your dreams, by simply making an appointment at a register office for a basic legal ceremony. You will say a few words and sign some paperwork which will cover the legal bits. You usually do this about a week before your celebrant-led ceremony or at your convenience. Exchanging rings and vows and all the other special parts can then be left to your wonderful, bespoke celebrant-led wedding.
You will also have to give notice which is just you saying that you intend to marry. The whole process, the basic ceremony and giving notice, costs around £120 (depending on where you live) and I will happily guide you through it.