Hello David,
As with the other respondents, I cannot predict your electricity usage, it entirely depends on you, however 1kW is not a quantity of electricity, which is rate of usage, more correctly you pay for kWh (kiloWatt Hours).
You should be able to estimate your own usage if you wish:
Check all the appliances you have, they should carry a power rating in Watts or kW (1000W = 1kW). It is easiest if you work in kW.
Work out how many hours each appliance will be used for each day, then multiply the power rating by the hours. That will give you the total power that each appliance will use in a day.
Add the results for each appliance together to get your total power usage. Now you can multiply that figure by what ever cost per KWh you choose.
It is important to realise that caravan hook ups are limited in the amount of current they can supply. In theory in the UK they should be able to provide 16A (= 3.6 kW) but some are limited to only 10A (2.3kW) or 6A (1.38kW) at any one time. The site operator should tell you the capacity of the hook up, and you should ensure you do not exceed it. If you should overload the hook up, it will trip the over current circuit breaker in the site box.