Do banks take (potential) income from rent into account when lending?

Hi,

I earn £17k and I suspect I would be able to get a pitifully small mortgage. Its a pipe dream but I would like to buy the house I'm currently renting a room in which I suspect will go on the market for £130/140k. Its a three bedroom house and I plan to rent out two rooms. Would the banks take this into account?

Thanks!