There is one called something like fluoconizole which isn't licensed but some docs will prescribe it as it is much more effective than other antibiotics. Also, get to the GP tomorrow if you can as it can get worse quite quickly if not treated.
I'd just go to your GP, but make sure the recetionist takes it seriously-it can get worse in a couple of hours and is excrutiating. Don't wait to see your midwife. If you can call her/him, they can press for an appointment asap.
Definitely push for a decent dose (a fortnight or more) of fluconazole. I lived with thrush for five months because I was being given just Canesten and I didn't need to. You should also get a cream for your nipples and a suspension for your baby's mouth.