Hi Tartanferret, I had relatives in Cromer and have consequently spent a lot of time there.
If it still exists and you want a good family B&B I would recommend the Birch House Hotel, close to the town centre, good parking on street or in car park adjacent to the rear.
The other guys in the thread have covered the main things to see, eat Cromer crab, checkout the lifebout and Henry Blogg (highest ever decorated RNLI man). Horsey Windmill on the broads is a good place to visit and the nearby will coastland is great if you like walking and big skies.
Lots of soil erosion issues so if you are into lost villages etc, worth checking out. There's a good museum behind Cromer church, loads of fossils etc.
You can find amber on the beach - looking for that can be quite fun. Take a pint glass full of water and chuck likely looking orange pebbles into it the odd one that floats will be amber.
There is a very rustic museum east of Norwich which had an "iceni village" not sure of it is still there but interesting if it is.
There is also a really good military museum with working tanks, jeeps and the like not far from Cromer - I'm sorry I really don't remember the name of it but it is advertised all round there.
If you are into traction engines and the like check out Strumpshaw Steam Museum and there is another museum nearby aswell with dozens of traction engines and steam organs, sadly my memory will not give up the name but the local tourist information will have leaflets.
Wildlife - seals and shorebirds, check out the boat trips and nature reserves (too many to choose from) - take your binos to get the best from it.
Bushcraft wise you are not far from Thetford Forest with it's 8th Army memorial and miles of Breckland (woodland and scrub - watch out for adders)
And lastly, if I have not rambled on enough already, Grimes Graves, which are Neolithic flint mines (two of which you can go down) and all their associated history and a small amount of exhibits (if you are into fkint knapping, this is the place for you)
Good luck and enjoy