Employment Contracts (3x Positions)

We are a small business and we require some employment contracts. We are looking to have a rolling contract with each person. The people are already in place and work on a self employed basis currently.

Person 1
Window Cleaner - Window cleaning, gutter cleaning, fascia and soffit cleaning. Power washing and gutter repairs.
37.5 hours per week. Hours to be worked on a flexitime basis. 20 days holiday per year (Bank Holidays included)

Person 2
Cleaner - Domestic cleaning for holiday lodges.
16 hours per week. Hours to be worked on a flexitime basis. 20 days holiday per year pro rata (Bank Holidays included)

Person 3
Administrator - Administration.
16 hours per week. Hours to be worked on a flexitime basis. 20 days holiday per year pro rata (Bank Holidays included)

I would wish to include within the contracts how the flexitime is calculated, what happens for sick pay, for window cleaning what happens during poor weather.

For the administrator I already have a contract in place, I would wish to renew the contract.