as she inherited all her husband's land,estates etc., on his death.

She was therefore a life tennant of the properties, and as I understand the situation, could have lived on enjoying all the income from the estates till her death when the properties then passed to Edward.

Below is a link to a post in the last Letters GR which explains this.

However, in her marraige settlement,which would have, no doubt been drafted with the possibility of the couple producing "hiers of their body", she may have been entitled to a jointure...and I'm wondering if the ammount of that was settled at something like £2000 p.a.?

I have not seen the Knight's marriage settlement ,but I'm guessing this was the sort of sums he would have been entitled to.

In practical effect, the charge on the estate would have been just the same had she had a jointure: the fact that she gave up her rigths to the estates and all the income from them, is a rather remarkable thing,IMHO.