Advice needed please on how much rent can i charge?

i have my own house in devon near usuall ammenities, shops, beach etc and i'm wanting to house share to help with my 750quid morgage, i have a huge furnished bedroom to rent out. my house is nice with new bathroom, garden, big kitchen n lounge...but dunno what rent to charge? i looked in the local paper to get ideas but wasnt any and estate agents nag me. wot du think? advice greatfully appreciated. thanks in advance.