Card Design for extra income

I’m struggling to find a part time job after my maternity is up next month and my FT role can’t go PT and we have no help with childcare. This means I need to give up my job to look after my child and we aren’t entitled to benefits because my husbands wage reaches the 25k threshold so we will be down a lot of money with me not working!

I am wracking my brains for ideas and seen that sites like Thortful allow artists to submit their designs and they print and send them.
I already do art and illustrations so did consider this option, every card you sell, you get 30p but it was never a get quick rich idea but more a stock them high/sell them cheap

Has anyone ventured into this area before and is it worth while.
I have run a small business for a while so know about taxes etc but I hate the thought of being unemployed and the extra income would be handy!