To the best of my knowledge, there's no official BBC Gallifreyan writing system(s) beyond what looks cool on props, but some of the fan-made Gallifreyan writing is a. gorgeous, & b. totally probable given what Gallifreyan we see on the show.
[Another pinner said: "I love you", written in Circular Gallifreyan. Maybe a large embroidery piece as a wall hanging- normal people can see abstract art, we'll see something really special.] I love the idea of embroidering Gallifreyan!
How to Write in Gallifreyan. Many hardcore fans of the TV show Dr. Who love the idea of writing with the alphabet of the Timelords. The creators of Doctor Who never made the language or alphabet official, but the most popular and widely.