MartynSinclair – you need a commercial licence, obviously. Plenty of firms out there. A decent commercial balloon will hold 12-20 people.
Private balloons are generally 77-90s. A 77 will hold two fatties or three skinnies, and a 90 will hold 3/4.
Be warned that there’s usually weeks of waiting before the weather is right, and even then flights can be scrubbed at the last minute. Balloons fly in the early morning and late evening, when the air is most still.
The problem is thermal. As the day heats up, you get a lot of thermal activity, and air shooting in all directions, which makes take-off and landing hazardous. On cold clear winter days, you can fly all day, sometimes.
Cost? About £125 a head for a 40-minute flight.