First up is the Kensington Brava contest. This year they're looking for novellas with all the heat and passion of their romances. The top eight contestants get mentored through the final rounds, so well worth entering even if you don't win! You can find out more here: Writing With The Stars. The deadline is mid August.
Mslexia managazine, aimed at women writers, is running a contest for full length novels. Entrants must be previously unpublished in full length fiction an should have a complete manuscript. Please note that there is an entry fee of £25. More information is available here: Mslexia The deadline is end of September.