You don't say if 3 day worker intends to return to work full time. Lets assume not, so total household income is 141k excluding bonus. You will be just outside CBI lending limits of 3.5 times income, unless bonus is guaranteed so you have a defined line of the maximum you can borrow (without applying for an exemption).
Borrowing 500k at say 3% will push your repayments up to 2,100 over 30 years. That looks fine with current income and savings.
However, banks will stress test your repayments by dding 2%, so again assume 5% brings you up to 2,685.
That's a big increase on your current mortgage. The critical thing is that you start putting away the difference now, each and every month, between your current mortgage and what it will potentially be, to prove you can afford it. It needs to be put out of reach, and not dipped into for things like a car deposit (I don't intend to be mean, but you asked similar questions 2 years ago, so I'm surprised you bought a new car). But, be realistic. Don't commit to putting away 2k every month and then realise you forgot some major expense.
Put aside extra money to pay off the PCP loan, and also as an emergency fund that you can dip into to even out cash flows over an extended term.
There are a few things that will count against you:
1. your age will limit the term of the mortgage. I used 30 years in example above, but you might be limited if you're in a job with a mandatory retirement age, or if you leave it much longer.
2. PCP, or any other loans. It's not the loan amount that makes the biggest difference, but the monthly commitment. It will count against your affordability, even if there is only a short term left on it.
3. Your cashflow negative investment property. Again this is a commitment that you have to meet every year, and is very exposed to interest rate increases (1% increase will require you to come up with another 2,800 cash each year).
Tell us more about the investment property:
Which lender is it with?
How much was it bought for? i.e. can value increase further without incurring capital gains tax?
Was it ever a private dwelling of either of you?
Edit: I didn't mean my post to sound negative! You've very good prospects of being able to do what you want, and you've a decent time horizon to plan it out properly.