bear in mind that I am travelling from Portsmouth Harbour, but we are going via Southampton, there are 4 of us travelling and the cost to ech ofus is £33.65. We will be buying on the day or nearer to departure. Our tickets will be 4 day returns (with railcard) from Portsmouth to Reading, 4 dayreturns (with railcard) from Reading to Banbury and a groupsave 4 from Banbury to The Hawthorns. We will change trains at Southampton and Banbury. Th train from Banbury goes to Birmingham Snow Hill. There is a direct train from Snow Hill to The Hawthorns.
Best place to work out fares is from the National Rail Journey Planner site. Split journey tickets often work out cheaper than single ticket journeys although not always, for instance, it is cheaper for me to buy a single ticket from Portsmouth to Norwich and back than any other way (and believe me I have tried many combinations!). Train tickets can be bought up to12 weeks in advance of travel, although obvoiusly this is not always practical (thanks Sky). Tickets get really expensive in the four weeks leading up to travel. They tend to stay the same price from 10 weeks before travel to 5 weeks before travel.
Hope this helps.