Hi PlotterC
There is a great and very popular bus service called the Coasthopper, which runs from King's Lynn all along the Norfolk Coast to Cromer and back several times a day. You can get on and off at whichever stops you like (Google Coasthopper for details of all stops and a timetable). You can use a bus pass, if you have one.
Someone mentioned Wells-next-the-Sea. If you enjoy walking, It's possible to get off the Coasthopper and spend the day here. When the weather is reasonable, there is a nice walk from the harbour along the sea wall, with views over the saltmarsh, to the pine woods bordering the beach. At low tide there is acres of sand, but note the tide times at the start of your walk (displayed in the harbourmasters window at the start of the walk) as this area is tidal and it comes in very quickly and can cut you off. French's fish & chip shop is opposite the harbour wall. The main shopping street is to the left of French's. Walk up to the top, turn left at Leftleys supermarket, then right, past the autobank, keep walking down this road until you come to the big Church on the left. Walk through the churchyard (safer than the nearby main road) and you will come to a gateway. Cross the main road to the white painted pub opposite, called 'The Bowling Green' and you will get the most delicious food and plenty of choices for lunch (need to book evenings).
There is another good, but long walk if you go alongside the harbour, past the sailing club and follow the path as it passes the fishermens huts and walk along the sea wall beside the saltmarsh to Stiffkey (pronounced Stookey). The Red Lion in Stiffkey does good food. You can catch the coasthopper at Stiffkey for the journey back. Make sure you have the timetable with you for the times!
If you like bird watching, take your binoculars, the Coasthopper stops right outside the Norfolk Wildlife Trust reserve at Cley. A Mecca for ornithologists. There is a visitor centre here, with toilets, shop and cafe, where you can sit and drink your coffee looking out over the reserve through a wall of windows. There is a bird sightings board, regularly updated, on the wall by the reception desk and to go across the road to the hides (boardwalk through the reedbeds all the way) you have to obtain a permit.If you go by car, there is a large car park in front of the visitor centre.
Hope this has been of some use to you.