@rjbell I'm in Rhoose myself but know exactly where you are! You should pop along to Barry Camera Club, it's down the road from you
One place not mentioned yet AND they have great ice-cream is the Mumbles Swansea. Verdi's ice cream
Merthyr Mawr is an excellent choice also, as is Talybont.
A little place I found today that's in the South, 10 mins from mine is Hensol Woods. I know the image is poor, I arrived late on in the day for a family walk aka a scout of the area

and it's like this all the way around.
Location scout images by
Gareth Williams, on Flickr
Pontsticill Reservoir in Brecon is good also as well as upper and lower Neuadd reservoirs