I really like Caistron Lake (open all year, except February))
It's about 20 mins away from Longfram, through Rothbury and Thropton.
Very pleasant drive as well. Your wife may like Rothbury - tea-shops, craft shops etc......shops.....
The 2 guys who run it, Cliff and Ricky, are both very nice, helpful guys and will sort you out with best flies, tactics etc.
Splendid views of the Simonside hills as you fish.
Only problem is they can have a weed issue but I heard it's not bad at the minute. Best to use a boat. You won't have to book for mid-week but best to for weekend.
They also have 2 miles of the Coquet so you can do river as well if you like (last week of salmon season).
Their site is:
http://www.caistrontroutfishery.co.uk/
Hope this helps & enjoy.
(ps - may be an idea to contact Grommit's shop if you want other suggestions)
Don