Just remember, if Wales was flattened it would be bigger than England.

But try Walking Offas Dyke from the Severn to the Dee which should take you a fortnight.

Or the Taff Trail from Kairdif (cardif) to Brecon 2 Days.

Or the Pembroke Costal Path 3 days ish !!!

Get Hesperis to PM me id you want more detail.

Gareth