With regards to the access it seems not even the council are sure if there is vehicle rights or not, here is the reply I got.
Thank you for your e-mail regarding the route near Tan y Clogwyn cottages. This particular route is recorded as an “unclassified road” on our records.
By implication, an unclassified road (or UCRs as we call them) carries public motorised vehicular rights though we would stress that this is not always the case. Indeed, the term UCR is a source of much confusion. I will attempt to explain the position as best I can.
The term “unclassified road” was created by the Local Government Act 1929 and there has been much debate over what the term actually means! It appears that all that can be deduced from the term is that an UCR is a highway maintainable at public expense other than an “A road”, “B road” or “third class road”. However, it should be noted that the term “road” does not necessarily mean that such routes provide public access for motor vehicles.
Where a road is maintained and used as a general motor road by ordinary traffic, has a sealed surface, road signs and white lines (for instance an “A road” such as the A470), its status (as a motor road) is unlikely to be at issue. The uncertainty as regards status lies at the other end of the spectrum, in particular, UCRs which do not have a sealed surface and those which are not used as a general motor road by ordinary traffic. We believe that the UCR near Tan y Clogwyn cottages falls into this latter category and, as far as we are aware, any motorised use of this route is probably limited to the landowners or those with private access rights.
As regards access to Maes y Gaer hillfort, the hillfort itself is part of the Coedydd Aber National Nature Reserve and we believe it is in the ownership of Natural Resources Wales. Please note, however, that land to the east of Maes y Gaer hillfort is private and permission would be required to cross such land. Information regarding landownership can be found on the Land Registry website.
I hope this information is of some help to you.