How do you tell your significant other you want to have sex?

We have bee together for almost 30 years, have 2 kids (8 & 6y/o) at home and both of us often are working for 70 odd hours a week...

If both of us end up awake[ish] and in bed at the same time then if either of us roll over and grope the other and the other responds - it might just happen