Count bathers, not guests
Choose capacity for the people likely to get in together. Not every party guest will use the tub at once, so planned sessions can work well.
Create safe zones
Keep cooking equipment, glass and electrical items well away from the water. Provide dry seating and a clear route between the house and tub.
Have a wet-weather plan
Hot tubs work in most UK weather, but strong wind, lightning and unsafe conditions change the plan. A suitable gazebo may help where locally available.