There is no reason why you cannot have a Celebrant led ceremony at a licensed venue. The venue has paid a fee to hold Marriage Services, which are conducted by a Registrar. This fee should be stated separately to other costs, as different Local Authorities make different charges and you can opt out.
A Celebrant led ceremony can be conducted anywhere within the venue meaning you are not restricted to the areas which are licensed. So if the venue has woodland area or grotto or fabulous garden these can be used (weather permitting).
Please remember that to ensure your Marriage is legal you will need to undertake the legal requirements at your local registry office. All offices conduct statutory services which are very simple, cost effective ways of undertaking the legal requirements. I would suggest contacting your local authority for an informal chat.
Choosing a Celebrant to help you create that special ceremony is an important step towards making your occasion a really memorable one. Why not take advantage of the free initial meeting I offer ? I believe it is important to meet informally to discuss your ideas and what I can offer. Meeting also gives us an opportunity to explore the type of ceremony that would best suit your needs.