coastal towns in UK?

I will be moving to Cambridge in August (24 days!) and my fiance and I are looking into taking a 3 or 4 day trip somewhere to celebrate my arrival and my new job (!) but are having trouble coming up with ideas...he's not as familiar with the south and hasn't lived in the UK for a few years, so all he can really come up with are places he went with his family that are too far for the time period we're looking for.  I'd really like to find a town on the coast so that I can soak up as much nice weather as possible after a really horrible wet and cold summer where I currently live.  Since our trip is limited to just 4 days, I'd also like to find someplace within easy train access of Cambridge/London.  Also, we're looking for something scenic and romantic, perhaps someplace with some nice historic sites nearby, and most of all, someplace that does not require a car, so a town that is quite walkable with places to stay and eat close together and near a beach would be ideal.  Any thoughts?  Tenby, Wales was our original idea, but it takes 7 hours on the train, so that will have to wait until we have more time to spare...

Brighton?

Here on the east coast there is Great Yarmouth which should be reasonably accessible from Cambridge by train.  It has the typical British seafront promenade full of cafes & other food stalls, amusements, guest houses, and so on, plus a pier and a wide sandy beach.  The main shopping center and market place is just a 10-minute walk from the beach.  (If you look in my UK-Y photo gallery you'll find a few photos of Gt. Yarmouth.)

Skegness should also be a fairly easy train journey from Cambridge, and is in many ways like a smaller version of Gt. Yarmouth, but without the docks and associated heavy industrial section that Gt. Yarmouth has.

Only went there once so far for just a day, night, and day, but I loved Portsmouth.

I'm a bit of a history hound so I loved soaking up the great ships, HMS Victory (didn't get time for the HMS Warrior)  and the 16th century Mary Rose and it's museum was fascinating.

There are some delightful bed and breakfasts, and the harbour area offers a pretty nicely developed open air shopping and dining district where you can dine overlooking the harbour; it's all very nice. The beach at Southsea is only pebbles, not sand, but the overall place was delightful. I'm sure someone on here will come along dissing it but I had a beautiful time there.

Southwold is around 3 hours by train away from Cambridge and is supposed to be a lovely little seaside town:

http://www.exploresouthwold.co.uk/

We've been considering going for ages because we want to see the Tim Hunkin Under the Pier show (yes, we're a bit geeky): http://www.underthepier.com/

David

Rye is gorgeous. There isn't as much to do as a city like Brighton, but it's painfully quaint. And you'll probably be more into each other than shopping, n'est-ce pas? Rooms at the Mermaid aren't as dear as you might expect (and there are plenty of other ancient inns and B&B's in town). I'm just blown away by this place.

Of course, you'd probably come through Brighton to get here.

My husband and I have gone to Great Yarmouth for day trips, but I wouldn't really stay there for a romantic weekend. 

My husband recommends Frinton or Aldeborough.

Southwold is very nice, but there isn't a train that goes there.  You would need to take a bus from the closest station, it is only 10 ish miles away, but it all depends on how easy you want your trip to be. 

thanks for all the great recommendations so far!  i can't wait to get over and start exploring!

How about the Isle of Wight? Accessable from Portsmouth so you can do both in one trip if you have a few days.

Vicky

Brighton would give you the city, seaside, and plenty to do. It's a short busride (10minutes) to the South Downs (beautiful countryside), a 45minute busride to the 7 Sisters Chalk Cliffs (amazing), and in general, a busride to any number of quaint villages such as Rottingdean, Alfreston, Faulking, etc. The train from london goes right into Brighton station, which is a 3 minute walk from the city centre.