Hi Lindylou....
To be honest, I think you will be lucky to find any rentals at £150 per month during the winter - unless you can find someone with the facility for you to pay for your own electricity and water. The cost of heating and hot water during the winter (when you can't rely on solar energy as much as the summer) is very high.
If you add in the cost of a cleaner as well, even if it's only once a week, that would use up most (if not all) of the £150 so most owners would not find it worth their while to let an apartment for that amount.
Unless anyone else has a different view?