Hi Roger
About 3 years ago we managed to sell a fairly large house in Cornwall - we tried a number of free & low-cost companies but the one that we sold the house through & the one that generated far more enquiries than the rest put together was
The Little House Company.
At the time they had a partnership deal with one of the bigger websites that carry estate agents ads (I think it was Asserta Homes) which undoubtedly generated a lot more hits than just their own site by itself. It looks as though Asserta has now become propertyfinder.com & Little House still have a listing agreement with them but they charge a bit more for inclusion on it (around £135 insteadof £89) - still well worth it though.
SWMBO spent some time taking digipics of all the rooms in the house & preparing a lot of supporting text to make up a Word document to use as a set of 'details' - it didnt look too bad printed out on a colour inkjet - I turned it into a website as well which was linked-to from the Little House website advert page. Because of all the detail that we put in the website/printed details we found that we had very few, if any, time wasters amongst the people that viewed the property & also didnt have to spend ages telling people all the details over the phone or in emails - we found it well worth the effort to over-do it once at the outset preparing the details rather than have to trot out the same stuff over & over to people that ultimately werent really interested.
We also found that not everybody that enquired about the house was net-savvy but they all had friends/children/grand-children that were, & had told them about it & given them the contact details.
As an aside, we also tried 4 consecutive Saturday ads in the property pages of the Telegraph which netted 3 or 4 enquiries & no visits - a complete waste of several hundred pounds; and also a free colour ad in Country Living which netted one local enquiry - so I wouldn't recommend going down either of those routes. If I was selling again in England I'd certainly give Little House a go - you could have your website built & the advert up & running before an Estate Agent had managed to come & measure up.
Richard