There are hundreds of possiilities - what sorts of things do you like visiting?
Countryside?
Train to Amberly, walk up in the South Downs, either a circular walk or walk to Arundel for the train back.
Train to Bentley, walk in the countryside there.
Train to Tring, walk along the canal towpath or up to Ivinghoe Beacon.
Train to Lewes, change for train to Southease, walk into the South Downs.
Train to Gomshall (via Guildford). Walk in the North Downs.
Train to Henley, walk along the Thames to Marlow for the train back.
Train to Goring & Streetley, walk along the Thames to Pangbourne for the train back.
Country towns?
Train to Oxford, Salisbury, Lewes, Arundel, Sherbourne, Frome, Castle Cary
The sea?
Trains to Brighton, Eastbourne, Littlehampton, Southend, Shoeburyness, Clacton, Walton on the Naze
Train to Portsmouth for ferry or hovecraft to the Isle of Wight.
Literary associations? Train to Rochester (Dickens) or Alton (for Chawton, Jane Austin).
Most Londoners like to take a trip to Brighton as there is no seaside so it's the closest one and easy to do from Victoria or most stations on the Southern rail network.
Train to Oxford, Salisbury, Lewes, Arundel, Sherbourne, Frome, Castle Cary
I like Jon's suggestions. The rail network in Britain is so dense and frequent, you can really go anywhere depending on your tastes and interests. www.nationalrail.co.uk
For regular travel I would suggest getting a railcard for a 34% discount on most tickets www.railcard.co.uk
Always buy an Off Peak Return which is generally only 10p to ￡1 more expensive than a single ticket
You could make it all the way to The Isle of Wight. The three mainland ferry terminals are all close to the railway stations at Portsmouth, Southampton and Lymington (all from Waterloo).
It's easy to travel around the island on public transport.
Brighton , Hamton Court Palace , Windsor Castle , Canterbury .. Blenheim Palace , many other places ....get a guide book .
Take a train from Marylebone (1.5 hours) to Warwick (it's a direct train). There you can see Warwick Castle. Don't forget the jousting show!
What are you interested in?
You could go to the seaside - Brighton, Whitstable, Bournemouth.
You could go to visit another city - Guildford, Bath, Bristol, Birmingham...
You could go to a tourist destination - Stonehenge
Canterbury or Brighton
windsor castle
