From TARDIS Index File, the free Doctor Who reference.

Nostalgia Tours was an intergalactic travel company. When the Doctor and Mel arrived at intergalactic toll port G715 as the 10,000,000,000th customer, they won a bus trip with Nostalgia Tours to Disneyland in 1959.

The Doctor noted that Nostalgia Tours did not have the best of reputations.

The tour included a group of Navarino tourists, who had undergone a form of shape-shifting to disguise themselves as human. The spacecraft, likewise, was disguised as a 1950s-vintage tour bus. Mel travelled with the tour, but the Doctor chose instead to follow in his TARDIS. The last Chimeron queen, Delta, also hitched a ride.

On the way to Disneyland, the bus crashed into a satellite and went off course. The Doctor, following in the TARDIS, helped prevent the ship from crash. The bus ended up landing at the Welsh holiday camp Shangri-La instead. The group made the best of it and simply transferred their holiday to Shangri-La while the Doctor and tour leader Murray worked to repair the bus.

These efforts were disrupted by a Bannermen attack, attempting to find and kill Delta. The Nostalgia Tour group attempted to escape in their bus-ship, but they were all killed by the Bannermen. The only survivors of the original tour group were Mel and Delta. (DW: Delta and the Bannermen)