To think we CAN live on the mortgage

Exactly!

@Gloriia It doesn't matter if your monthly income is 1k, 10k or 100k. More than a third of it shouldn't go on a mortgage. Use your savings.

It absolutely matters if your monthly income is 1k, 10k or 100k. The basic rule of thumb might be to spend less than a third on a mortgage but: a) it's guidance rather than a hard and fast rule, and b) it really doesn't work at the higher and lower ends of income distribution. Those who have a very small net income will need to spend more than that, and those on the higher end can afford to do so because of the £ value of the disposable income after housing.

Here's my tiny violin. How will you possibly cope.

Otoh with that much money, surely you can work this out for yourself or pay someone to do it.

Can I ask what your career paths have been please? I would desperately like to have these problems.

& OP also factor in if you both want to stay full time. If your little one is still quite young you don't know how you'll feel about this in a few months / year.

This.
If is about 5000 each and one lose the job the dipping in the saving won't harm much in a couple of months. If the split is 9000 over 1000 the savings may suffer if one lose the job.

There’s a forum on Reddit you may find will have better answers than MN too @JaneEyre40 it’s called HENRYUK. (high earner, not rich yet) for those earning over 100k.

This was my husband and I’s wage split before I needed to reduce my days down to 3 days to take care of my Mum. It’s been a brutal reduction from my end!! But it’s not something we could plan for. We now take home circa £5,250 and £2,500 (including pension reduction for highest earner) and our mortgage is £1610. Nursery is £600 which will reduce down to £400 when the new funding come in in September. It sounds like a lot but we actually have no money left at the end of the month and I wouldn’t say we do anything!! We rarely eat out or have hobbies…

My best advice to settle your mind is get income protection and critical health insurance so if anything happens you are covered.
It won't be long until your child starts school so no big nursery fees.
Get a good mortgage broker to see if you could get a better deal. Highly recommend Cheshire Mortgage Group.
Also being savvy for example, use go compare for car insurance renewal. Water metre saved my mum £20 a month, getting the best details for the broadband, being in contract makes it cheaper. Check your electric and gas tarrifs to make sure you are on the best deal. Try to keep saving as well.
Also check you are maximising pension contributions with your employer. Make those savings work for you, I take it you are maxing the cash isa which is tax free to save.
Trry not to stress, you are in a brilliant position with good savings. Also follow Martin Lewis, he offers great money tips. Also use top cashback helps.Hope this helps.

I hope you dont work in Finance

Couple - Earn £10,500 a month
Mortgage - 3,700 a month
Nursery - 1,000 a month

Salary 1 - 4,200 monthly net
Salary 2 - 5,200 monthly net

4,200 + 5,200 does not equal 10,500

Whilst it all sounds very doable with the things you’ve listed I would be cautious purely because of my back ground.
My parents brought their dream home when we were younger, all fine and doable at the time.
One parent (higher wage earner) then become chronically unwell with. Life long condition and had to give up work.
The pressures of keeping the house (because one wouldn’t downsize) cost them their marriage so the house had to be sold anyway.
If it’s your dream then I would say go for it, however if you can’t afford in with one wage or have to rely on commission/bonuses then the dream can become abit of a nightmare.

I think you’ll have plenty! But then it depends what you mean by afford.

What jobs do people actually do to take home this sort of money?

This. It doesn't matter if your monthly income is 1k, 10k or 100k. More than a third of it shouldn't go on a mortgage. Use your savings.

I presume you'll have a lifestyle to match the income so probably won't shop in aldi and holiday at Hoseason? It'll all add up.

I think in these desperate situation a go fund me would really help you

What about pensions? We earn more than your household but try and pay at least 75k into pensions each year otherwise you’re wasting a huge amount paying unnecessary income tax at rates of us to 60%.

Your financial planning appears more than a little naive.

We are in a similar set up, only my husband brings in close to 10 and I’m a SAHM. Our mortgage is 3000 and we have no childcare costs but our daughter has SEND so that’s tricky to navigate. You’ll be absolutely fine. Keep adding to savings, get a survey done obv so no nasty surprises like the roof falling down. We have a 5 bed detached as we moved out of London for 850 which we love!

Make yourself very familiar with too good to go, local food banks and olio !

£3.7k/m is £700k over 25 years.

Which isn’t a lot of house in much of London, insane though that may be.