I'm in a similar situation and so far, things are OK. My daughter and son in law moved back from Turkey about three weeks ago because my daughter has a new job in the UK. My son in law has also found a new job in Germany and once his visa has been approved, will be there during the week and then he will either come here for weekends or my daughter will go there. In the meantime he is working from home here.
I've worked from home for many years but am starting to reduce my hours now thst I'm retirement age, and so have rearranged my home office as a bedroom for my daughter and son in law, with a sofa and a smaller desk. My daughter has always been really awful with keeping her room and the rest of the house clean and tidy but so far, things are very different. They are being respectful of our house and the kitchen in particular. They have their own shelf in both of our fridges and I have emptied out a mini freezer that I bought at the start of the pandemic for them. I've made some cupboard space in the kitchen as well.
Food isn't an issue as they are both Muslims and only eat organic food, so most of the time they are buying and cooking their own food. The only slight issue is the bathroom; we only have one bathroom and a separate second toilet, but in the mornings they are both fine and leave us to use the bathroom before they go in. Bedtime can be a bit more difficult because they both spend hours in the toilet before bed, and I do get irritated when I can't get into the bathroom when I want to go to bed at 1, but nkw thst my daughter is about to start her new job, I assume she will be going to bed earlier.
They have also been extremely quiet when they've been getting up in the small hours to pray and to eat before it gets light during Ramadan. They are doing their own washing and cleaning.
I was a bit worried before they arrived but so far, there have been no major issues. My son in law in particular is very concerned about us not doing too much in the garden and outside and seems to think that we are unable to do things any more becasue we are in our 60s, which can be irritating, but it's meant in a good way.
I'm not finding the thought of the next year is filing me with dread and although my husband and I have enjoyed having the house to ourselves for many years now, it's nice to have the company. It's not really costing us anything extra to have them here, apart from the cost of the new bed, bedding, and towels thst I bought. I realise that it will be very different for the OP having to contend with a baby as well, but I think it could well be doable.