Visits have gone down on Tuesday and Wednesday of this week has been lower 20 to 80 % lower of last weeks Tuesday and Wednesday.

Anyone else the same? My site is UK based...

About the same here. No significant changes.

Have you recently made any modifications to your site, or changed your method of advertising?

I don't advertise at all and google hasn't indexed me, I relay on my back links 148 in google... I have redesigned my site, I would have thought this would boost visits. This might have something to do with my visitors being in the UK, its holiday season, kids off school and people seeking warmer climates...

When you redesigned the site, did the name of any of your pages change? Or the content move? Maybe the links pointing to you are no longer pointing to a valid page / file name.

no, the pages where replaced and all original content stay just the deisgn changed and the titles were edited, thats about it.

Check your backlinks to make sure they are still in place. 80% is a big drop, and there must be a reason for it.

Even with the natural summer decline of traffic, it would not come close to 80%.

Check your stats to see where the traffic is no longer coming from.