Re:
It's worth what people are prepared to pay, but it is a 1970-80 low-mid range ladies bike - which appears to be in good condition. EBay has a multitude of similar bikes from various manufacturers which are advertised for anywhere between £20 and £300 (or there are the optimists who list their's for more). In reality you would be looking at £60-£100.
Good luck if you sell it.