Hi, Chris!
As Brian has more or less said, don't bother!
Auto-Loco is excellent if you want 3-rail Hornby Dublo or old railway books! Last time I went there (first and last time since it changed hands), I could barely walk round for all the boxes of 3-rail track covering the floor, and the boxes of second-hand books being priced onto some racks.
GE Models (used to be in the old Waterloo WH Smiths on the platform at Sheringham Station) is now just a stain on an empty platform. The souvenir shop in the main station building has, as has been said, a reasonable stock of Dapol special edition 4-wheel freight stock.
Starlings, the toy/book/stationery/newsagents/post office only stock Hornby and Peco at retail list prices (at the lowest!)
Nearest decent model shop, as has been said, is 'round the corner', nearly 30 miles west at Hunstanton .
Inland, in Dereham (or East Dereham) there is another avoidable branch of Starlings, but also Hobby World, who also have a shop in King's Lynn (in a tool shop). Good Bachy/Farish/Hornby/Peco/bits & pieces selection in Dereham and at a small discount on RRP (or perhaps that's just for regulars, but try asking if he'll haggle. Partly depends on who is behind the counter - the boss seems to be the one to ask!)
If you still have to go to Sheringham, the only good value deals are in the crab sandwich kiosk near the seafront - definitely makes the day worthwhile!
12 inch to the foot scale at Sheringham Station (NNR) and Weybourne is the other redeeming feature, but it's a no-go zone for models!