This little show only ran for one season back when I was ten years old. It was set in a Gentlemen's public lavatory, which is where the title came from. In Britain it was traditional to pay one old (pre-1971 decimalisation) penny to use a public toilet and the phrase "going to spend a penny" is still a euphemism for using the lavatory.
I don't remember a great deal about the series. I don't think it was particularly funny. Bob Todd (who could be a wonderfully eccentric ensemble player) played Dan, the long-serving lavatory attendant who took real pride in having his domain spotlessly clean and polished. Kervork Malikyan was his immigrant assistant Ali (with all the usual shtick about his accent and poor grasp of English; well, it *was* the 1970's). Ivor Salter played a local councillor and regular customer - the running gag here was that when he left there was always some graffiti scrawled on the wall and Dan would refused to believe that an elected public official would do such a thing.
So there you have it - everything you wanted to know about 'In for a Penny' but were afraid to ask.