just bought another keep and not had one for ages and believed that the way to the roof was to lock something like a table on ground floor then cast e-field on floor above it and stand in it and log out and in again but no it doesnt work. Can the roofs still be accessed?

As far as I know the method you mention is illegal.
It does depend as usual on which GM you get though.
The last word from a lead GM was, it is legal to decorate your roof. The methods to get onto the roof are illegal.

Good luck figuring that one out.

I asked a GM quite some time ago,and they actually told me how to do it, with the caveat being for decorative purposes only.
Easiest way without having to fiddle with tables or forges etc, is to stand at the top of the staircase cast efield on yourself, log out then back in real quick.