Hills: hilly – but nothing too big;
Traffic: generally quiet;
Surface Quality: varies;
Refreshments: lots of good pubs, also occasional tea shops.
Hertfordshire has great options for country lane skating. One option is to start and finish in Knebworth. The road surfaces are of variable quality: the more minor roads can surprisingly have smoother surfaces than say a B road (perhaps they are made a bit rougher to improve stopping for those using tyres!). There are many quiet roads (particularly the yellow ones on Ordnance Survey maps): and as horse riding and cycling are common in this area this appears to make drivers more cautious.
http://www.gmap-pedometer.com/?r=3259569 (23 miles). http://www.gmap-pedometer.com/?r=5109787 (32 miles). See also: http://littlegreenride.blogspot.com/ for ideas – this is a regular cycling group – but the routes they do are generally also good for skating.