Winter coat plus size !

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Help pls

I am a awkward size 20 no boobs ,but large upper arms , wide hips , I need a coat suitable for school runs , but I don't like to get too warm/cold lol .
I am on a strict budget might be able to find £50/60 quid ATM I am doing the school run in a sweat jacket and getting soaked ( live In a very very wet town ) .
I used to have a super dry coat I loved but I got fat so it doesn't fit , I am trying to lose weigh to get back in it , but it's going slowly.
Anyone know of a nice cheapish winter coat pls .