16 is the legal age at which girls can give "valid consent" in the UK, but that does not mean that a relationship with an adult with such a big age gap is a good thing. The reason consent is at that age is so that 16 year olds can safely explore urges that come naturally without being branded criminals. I think that the more developed and substantial relationships (sexual or otherwise) that occur in later life (early-twenties and beyond), are not what your average 16 year old is looking for or capable of handling. Go for someone a little closer to your own age, or at least a little older than this girl.