Sorry, can't help much - single plays - as well as whole series sometimes - can be extremely difficult to track down even on the internet. Probably a contemporary publication with TV listings would be the best - I know that one of our members here has copies of TV Times from the '60s and '70s, so might be able to help (yes, I do mean you, Cornershop!).
ITV had a series of plays running from 1963-74 which went under the title of Love Story. I'm just wondering if your play could have been one of those - you know, a twist on the usual heterosexual relationships we generally had on TV back then.
There was a BBC2 play shown in 1974 called Girl, which I vaguely remember seeing. It starred Myra Francis and Alison Steadman and I think they are members of the army or the police force or some profession in uniform. They share what is said to be the first lesbian kiss on television (although I'm not sure that it is the first). Obviously, this was quite 'daring' for the early '70s and I'm wondering if you can remember how 'graphic' your play was. One would expect to be able to find it fairly easily if it concerned lesbianism and was being shown around the same time as Girl, in an era when the depiction of such matters was rare.
E.