These figures might help - we put aside £300-£400 a month for repairs, maintenance, replacing broken household items: £100 a month is repaying an interest free loan for that (for next 3 years). Supply and fit of a new toilet was close to £500. Getting overgrown trees cut back and removed £300. Removal and replacement of mouldy plaster £800.
Your interest costs are key - you might pay back 2x what you’re borrowing to buy the house. If you can get 20% loan to value instead of 19% you might get a cheaper rate, likewise if you have two incomes as it should be lower risk of default.
It’s important to factor in retirement as well including for your wife. Hopefully she has some state pension credits if she worked earlier in life or claimed child benefits, two salaries and buying a £500,000 vs £575,000 property would make a big difference - you could save on tax by putting more into your pension maybe if your wife was working. Instead of paying £150,000 (the £75,000 plus interest) on extra housing cost that money could go into retirement.
You could:
Run the calculation of how you’ll afford to maintain and run the house including estimated costs for council tax, bills, insurance, repairs etc.
Look at what adding a second income does to your figures. Get a second income before buying.
Look at buying towards the lower end of the budget, could you get a two bed place or one that is more basic and save on costs.
If you’re getting a 3+ bed home could you rent out a room to create extra income.