On the first point, no. It's not worth the risk.
As for the rest of it: that's the kind of advice you should be getting from the NHS. Here's the current advice from the RCOG for your other half:
https://www.rcog.org.uk/en/guidelin...nancy/covid-19-virus-infection-and-pregnancy/
The government do list pregnant women in a relatively high risk category with respect to their isolation policy. They're not saying you have to stay away from her. But I it's made clear that she's more vulnerable than most:
* if one member of your family or household has a new continuous cough or high temperature
** if you live alone and you have a new continuous cough or high temperature
*** for example cinema, theatre, pubs, bars, restaurants, clubs
**** for example via telephone or internet
1 such as anyone instructed to get a flu jab each year
https://www.gov.uk/government/publi...protecting-older-people-and-vulnerable-adults
But most importantly, I think you should primarily take the advice of your missus' GP.