I take it you mean Brindisi on heal of Italy. I think this is a really nice destination for overland travel from the UK as there are a few options which means you could do a circular route (all be it a fairly squashed circle!). On the way out you could get the Eurostar from London to Paris and then continue on the train to Milan, from Milan you can get another train to Brindisi . You could in fact go via a number of other Italian cities such as Rome, Bologna, and Naples if you wanted to see a bit more of Italy.
Rather than going back the same way as you go out you could go back to the UK via Corfu, sounds a bit odd I know but from Corfu you can get a ferry to Venice and from Venice you can get back onto train system and head back to London. If you want to incorporate a ferry this might be the best option as you are based in Oxford I think the Eurostar is a better option rather than trying to get one of the cross channel ferries to mainland Europe.
As there are a number of options you can obviously mix and match on the routes I have suggested or look at variants of what I have suggested. The maps on our European ferry page http://www.flightlesstravel.com/plan/european-ferries/
may give you some alternative ideas for ferries too and from Italy.
Hope this is of some help and I have not made this to complicated!