I hope your well Inshallah.
Ahhhn i rember handing in my disso this time last year was hectic:exhausted .
I did Science and i cant spel, so im not much help but Iwhat I would suggest is talking to your lecturers to find out any current topics that will be benificial to you or your career once u graduate..also contact students and staff and look at samples of dissertations...read around topics that intrest u and speak to others that have graduated in your field by contacting the Alumni (if u have one) speak to your librarian ad and finaly only do a dissertaion based ona topic that u will be happy with
NEVER CHOSE SOMETHING BECAUSE U THOUGHT UD GET A GOOD GRADE OR COS SOMEONE ELSE SAID IT WAS A GOOD IDEA.AT THE END OF THE DAY U GOTO SPEND LIKE 1000000 HOURS ON IT SO AND IT WILL AFFECT UR GRADE and your life till u finally hand it in.
Inshalah it wil be a pleasurable experince and one from which u will learn a lot bout your self inshallah.