Hi
you're retired & on a low income.
we're going in (are in) a recession. Tread carefully putting 'everything in' to this house right now as prices may come down & you don't want to have significantly over paid.
Is this house somewhere you would want/be able to live for the rest of your life? If it's not, definitely don't do it.
then you have to sort NEED from WANT. & prioritise. (I did my bathroom first because it was horrible & although it was 'useable' in that it had a functioning toilet & running water, it didn't have a decent shower OR daylight. So I prioritised a new bathroom & a skylight. I LOVE it & it's been done several years now. The kitchen is still waiting! Though that's been delayed, this time, by covid, previously surgery etc etc. i wish I'd been able to do it earlier as it's going to cost a LOT more now (installation, appliances, tiles etc. the basic units from DIY kitchens I don't think is much more)
knocking the rooms together might not be expensive (if not load baring) but could be if it needs steels etc. if it's something terribly important to you, you should have found out before best & final.
there was a thread here recently about bathroom prices. Obviously labour costs vary enormously depending if you have family/friends who can help you install it or if you need to pay someone to do it & where you live.
but the bathroom suite itself depends on shopping around & how fussy you are. I knew exactly what I wanted & spent ages looking to get the pieces individually but others are happy to buy a second hand suite for £500.( less if you can find one about to be skipped) or around £700 for a new one (in a dated style).
my kitchen cabinets are going to come from DIY kitchens. The actual company not the bit of B&Q). I have researched a LOT & have found them to be, by far, the best quality for money.
ikea are good & I do like some of theirs, but unless you have family/friend that's skilled & patient to do it fir you, it'll cost you a LOT more for a tradesperson you fit it (no recess at the back of the cupboards so they need to have bits cut out for pipes etc.
Dont forget to check for access to bus routes/shops/Drs etc (even if you currently drive).
house buying in Retirement, especially alone & when you don't have bundles of money can be very emotionally difficult as it's all about winding down your life, not planning for the exciting things, like having a family or using it as a pad while you travel.
I'm in the process & it's really taking a toll on me. Before the CoL & talk of recession etc. Before an accident I had last year, I was looking at different properties, (the Accident really showed me what was important to have near me, bus link to hospital for rehab as I couldn't drive, Drs in walking distance, shops, chemist near by etc etc). I love my place now, previously I was looking for more garden & more living space, but now I'm looking for other things. more suitable for retirement.
sorry lots of waffle, but I hope it helps you in some small way.
best of luck.