no vehicles except for access

[sjwright]

What exacly does this mean? can I drive on roads with this and what would happen if I did?

[kira000]

It means that for some reason, the road is closed to everyone other than people with a legitimate and pressing reason to access the road, i.e if you live on the road that is closed, or your business is on the road. It is not open for people to use as a through route to anywhere else.

[Buenchico]

Further to Kira000's post:
If you drive past the sign, other than to visit a property on that road (e.g. if you were using the road as a 'through route', to enable you to take a short cut), you can be prosecuted under Section 36 of the Road Traffic Act 1988. The maximum penalty is a fine of �1000. Your licence will also be endorsed with a 'TS50' code and 3 penalty points.

Chris