Hello, I posted a question recently about which train to take from Gatwick to Victoria Station. I received great advice. We are staying at Victoria Inn on Belgrave Road. I have another question regarding the various transportations options. We will take the southern train to Victoria but I'm not sure what to purchase .. travel card or Oyster card. For some reason I find it all confusing. :( we will be in London for three days .. arrive on a Tuesday at 10 am and then we are taking a train to Watford on Thursday evening to stay with relatives. We would like to take advantage of the 2 for 1 deals, if possible. Can you please recommend what we would need to purchase .. and should we buy it in advance. Thank in advance for your patience and advice! P.S.