I work through agencies, I'm in the midlands.
FE colleges usually only pay the hours you are teaching, schools usually pay a day rate and an agency should negotiate on your behalf.
I mainly do long term although I have doe the odd day or half day. Because my subject is mainly 16+ I am often without work from Mid may until September but then I work fairly solidly until the following May.
My payroll provider keeps a % of my salary back to pay through the holidays.
I'm paid through an umbrella company, most agencies prefer to do this and it means that I can claim expenses as I work rather than fill in a tax return at the end of the year. Useful if you take assignments out of area and stay in a hotel (I did 6 weeks in Cambridgeshire).
My rate varies between £100 - £150 per day when working in schools.
The current school have me basically working like a permanent member of staff in their department, in other schools they have just given me everything to cover so Spanish, dance, maths, English, art - possibly more.