OK I'm a general manager of a recruitment agency employing temporary workers and my own staff so a bit off an expert in this field.
1) There is no law requirering a employment contract, there is a law for a letter offering employment.
2) Sick pay is not required to be paid untill you have been off sick for 3 days (i.e. the first 3 days off sick are unpaid) then legally SSP kicks in at arround £70 per week. You are considered to be off sick untill you return to work, therfore if you were off sick on thursday day -1, friday - day 2, Monday - day 3, thus no entitlment to any pay.
3) Legal holiday entitlment is 20 days a year, bank holidays do not figure into this in anyway, so it is 20 days total. The goverment are not happy that employers are not paying Bank Holidays but also understand that some business' need to opperate on said days and to compensate people for those days without forceing companies to close are giving us from 1/10/07 an additional 4 days a year making a total of 24.
Any questions give me a shout.