Tell them how sorry you are for not turning up and tell them you didn't have protective clothing,
Go to the interview tomorrow, see how it goes, if your offered the job, buy a decent rain coat and a briefcase, therefore paperwork won't get wet.
As for the company, they obviously like you, ring them up and tell them about your situation, if they tell you not to come in, then it's their loss but if they give you another try then accept it. It sounds like they want you.