From what I understand (37 weeks here), pregnant women are vulnerable in the third trimester. This is because some previous cases of pregnant women with covid have gone into labour prematurely (which means babys lungs aren't fully developed and means they have a difficult time fighting off covid if its passed from mother to baby (either through face to face or vertical transmission)).
If you have a heart condition and are pregnant, you are at a high risk and need to be shielding.
Other than that though, your standard hand washing, clothes washing, social distancing, face touch avoiding should be enough to keep you safe.
Work does need to risk assess you (this should happen regardless of covid) and your role. They need to provide an adequate space and safe role for you to complete your job. No heavy lifting, no exposure to chemicals etc.
They also have a responsibility to all their workers to make sure that your work environment is adhering to protective measures for preventing covid transmission. Social distancing, PPE if required etc. So their risk assessment should not only include Covid measures but also your pregnancy specific ones.
If they do not have any adequate replacement jobs for you, you should be sent home and still get paid. Pregnancy is not something to be punished. It is your right to be pregnant and start a family should you wish to do so. So there should be no risk of punishment.
If you feel work are not doing what they should be, you can get some great advice from Maternity Action.
For those who are pregnant, keep an eye on Marernity Action, RCOG, NHS, WHO and Government website. Particularly the first two.
Hope this helps some of you.