As you mentioned enjoying beer, I had a look in this year’s CAMRA Good Beer Guide. If you’re not familiar with this, it’s a yearly publication from a long-standing “real ale” campaign group. Pubs are chosen for entry mainly on the basis of the quality of the ale, but other notable aspects are also mentioned.
Aside from a Wetherspoons, there are two Salisbury entries that do food, and both are marked as explicitly child-friendly:
Rai d’Or, 69 Brown Street, SP1 2AS
01722 327137
http://raidor.co.uk/
Thai food and two local beers in a 13th-century building.
NB not open on Sundays, so this would be one for Saturday night.
Railway Inn/Dust Hole, 59 Tollgate Road, SP1 2JG
01722 324537
http://thedusthole.vpweb.co.uk/
Very standard pub food, but you might find it worth a visit for the beer. It isn’t clear whether they do the regular menu on Sundays, or a special Sunday menu (which as you surmise usually stops fairly early, 5pm, 6pm, or even earlier).
Hope this is helpful. I have no personal experience of either place.
