I have been doing part time freelance for the last 16 years+ and always seem to be offered lots of weekend work.
I now pick and choose what I want to do but around our area there seems to be a lot of work available.
Make sure you are set with the tax man and the NI people. Because I am partime I have an exemption from paying NI but pay tax and claim back all my expenses (clothing, mileage, postage and phone charges).