Does this sound like a good plot?

[TheMessyCleaner]

This is not autobiographical btw!

Woman in her late thirties starts a new job. Is seriously skint, bailiffs at the door etc. Has a son and a partner who is jobless but very roguish and funny. Her main features are her good looks and determination to better her prospects.
In the new job she meets a bumbling, overweight very chatty woman who takes her under her wing and shows her the ropes. Main character doesn't let her guard down to anyone. From talking to colleague she finds out that the colleagues wife is a very successful psychiatrist, and their life is everything that main character dreams of.
She plots with her partner to seduce the wife and replace the colleague, keeping her partner on the side and sending him money/shagging him still.
She starts to manipulate situations to become closer to colleague and also to make her relationship unravel. Main character is very aware of being vulnerable as oppose to her past way of seducing men. Her theory is that a rich woman is less likely to trade their partner in for a younger model and that she would have to appear as more helpless to the wife, and hope that she wants to 'rescue' her from her situation.
The end is going to be something like she gets rejected by wife and all of her assumptions were wrong. The moral (if you like) being that very often the people we pity are the people who have made the best choices in life (or something.)

I’m not sure about the plot but I do feel the bumbling overweight person is overdone and makes me think less of the author. Could they just be bumbling?

I think it's important as it shows the shallowness of the main character. Everything she thinks about the world is quite shallow and life isn't like that. She needs to realise that there are people aren't there who don't see the world like that.

First thoughts are that a psychiatrist would see through these manipulations from the get go so the story would have The End at the end of the first chapter. It also seems a fairly improbable story line - a rich woman is less likely to trade their partner in for a younger model and that she would have to appear as more helpless to the wife, and hope that she wants to 'rescue' her from her situation - & tbh a bit tone deaf to use a committed, married lesbian couple as a vehicle for this scam.

I'm friends with a couple of psychiatrists, both of their wives are pretty astute. If you've ever spent much time with psychiatrists (the sane ones anyway, and from your premise she is) you'd know they tend not to marry idiots, so your main character is on to a loser from the start really.

The overall premise could have legs hut I think it's the wrong situation.

It sounds like a confused version of Henry James's The Wings of the Dove, only in that, the 'mark' is a dying American heiress the conniving heroine wants her secret fiancé to seduce and marry so that when she does, they will get her money.

So your main character is going to seduce the (gay?) colleague, or her psychiatrist wife? Why does she need to replace the colleague at work if she's seducing the colleague's wife? Is she planning to keep up the charade indefinitely, or is there some plot to get her hands on the money? Is she bi, or is she just planning to pretend to be attracted to women for the rest of their life? How old is her son, and is she planning to drag him into the new relationship or leave him with her partner?

I think you may be overestimating the riches of successful psychiatrists, too!

I was going to point out the 'riches'of psychiatrists too Frangible, but thought he may have had an inheritance or summat.

She.