I've always like Canon cameras. This Canon EOS 250D Digital SLR Camera with 18-55mm IS STM Lens - Black | Wex Photo Video is within your budget and an excellent camera for the money.
I mentioned it earlier, but in case you missed it an Olympus EM10-II or EM10-II and a 9-18mm lens. You could even get a used Olympus EM1.
If you don’t need a viewfinder then Olympus E-PL8 would also be worth a look.
A used OMD E-M1 or M5 would also do a great job.
Your current lens has a field of view equivalent to 18-35mm on a “full frame” sensor (used to compare lenses on different size sensors).
On the micro 4/3rds sensor in the Olympus cameras you need a 9-18mm lens as @snerkler has suggested.
As your Nikon lens looks to have been quite expensive if it still works you could look to sell or trade it in even if the body is dead.
Online places like Wex, mpb and camera jungle will part ex against new purchases. You can often save a lot of money by buying used.
Good suggestion and worth a look, also a tripod if you don’t already have one, for taking HDR images as suggested above.
The Canon 250D has a crop factor of 1.6 so that 18-55 lens has a 35mm frame equivalent field of view of 28.8mm-88mm.
I suspect that for room interiors you'd need a wider lens than the standard Canon kit lens - unless you were prepared to stitch together multiple images.
The OP currently has the equivalent of 18-35mm on their J1 (Nikon 1 Nikkor 6.7-13mm f/3.5-5.6 VR & 18.5mm f/1.8 lens reviews: best performing lenses in the range - DXOMARK)
It's also a stabilised lens which will be helping with handheld interiors.
As AMC says, the 18-55mm on a crop is not going to be very wide in comparison to his old camera data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
Fair point, if the very wide angle is needed I think there’s an efs 10-18 that’s reasonably priced.
I would actually try and use an iPhone 11 Pro Max. With the ultra-wide, standard and zoom lense and very clean night features, you've got everything there that can match what the OP has got. It truly is very good. The only thing limiting will be one's own skills.
You have the choice between cameras with optical viewfinders or the ones with electronic viewfinders (EVF). With the latter try to get the highest resolution EVF you can.The EVFs in the Canon M50and Olympus EM10 MKII are 2.36MP vs just half that res in the Sony A6000,
Canon 4000D with 18-55mm lens (28.2 to 88mm equivalent) £270 plus EF-S 10-18mm lens (16mm to 28.8mm equivalent £199 Total: £469. Absolute bottom of the range, no frills but is reviewed as taking decent photos.Poor low res rear LCD. The EF-S 10-18mm lens gets good reviews and has image stabilisation.
Canon EOS 4000D review: Is this the best budget DSLR yet?
Canon EF-S 10-18mm f/4.5-5.6 IS STM Review
Nikon D3500 with 18-55 VR lens £389 (27mm to 82mm equivalent) plus Nikon AF-P 10-20mm f4.5-5.6 G DX VR lens (15 to 30mm equivalent) £218 Total £607. Nikon D3500 review
Nikon D3500 Review | Photography Blog
Nikon 10-20mm f/4.5-5.6G VR AF-P DX Nikkor Review
Canon 200D body £458 plus the EF-S 10-18mm lens £199. Total £657 or £508 with 18-55mm lens plus again the 10-18mm lens Total£707.
Canon EOS Rebel SL2 / EOS 200D Review
Canon EF-S 10-18mm f/4.5-5.6 IS STM Lens Review
Sony A6000 (£395) with Samyang 12mm F2 (£299) Total £700. Equivalent to 18mm but manual focus and manual aperature. Although this may make it much more difficult to use if you are not used to older manual film cameras. However the A6000 has good focus peaking although its electronic viewfinder is not the best and is low resolution compared to the Canon M50.
Or A6000 with the kit 16-50mm lens (24 - 75mm equivalent) £459 plus the samyang 12mm Total: £758
Sony a6000 Review
Gear Review: Rokinon (Samyang) 12mm f/2.0 NCS CS Wide Angle Lens - Trail to Peak
Canon EOS M50 body £469 with EF-M 11-22mm lens(Equivalent to 17.6mm to 35.2mm) £283. Total £752
Again this Canon wide angle lens gets good reviews.
Canon EOS M50 Review
Canon EF-M 11-22mm f/4-5.6 IS STM Lens Review
Olympus EM10 MkII body £379 with 9-18mm lens (equivalent to 18-36mm) £405. Total £784
Bang for the Buck: Olympus OM-D E-M10 II Review
If you want to buy new the Nikon D3500 seems closest to your stated £600 budget or the Canon options using the same well reviewed (for the price) EF-S 10-18mm zoom lens. The M50 with it's wide angle zoom is another option at higher cost. From the reviews the two Canon wide angle lenses perform better than the Nikon one.
But you would get a lot more for your money buying a 2nd hand higher spec camera with low use.
One of the higher model Nikon or Canon cameras costing the same price used as the new lower spec ones would still let you use the cheap wide angle lenses available for them. Unfortunately the other makes lack these cheap wide angle zooms so unless you can pick up a 2nd hand wide angle lens for them you still have the extra cost element.
If you can wait until November there is the chance of getting much better prices in the Black Friday sales coupled with the cashback programs the manufacturers run at that time of year (often double cashback so a nice saving to be had). You can find the prices for cameras and lenses at www.camerapricebuster.co.uk
If you want to save a bit of money you could buy frrom the grey market at HDEW or Panamoz although at the lower price range they can sometimes be more expensive than buying from normal retailers. For the Canon 10-18mm HDEW is £189, Panamoz £260 vs the £199 most retailers are seling them at.
Of course the most cost effective solution would be a user J series body.
They're pretty cheap!
Search - Nikon Mirrorless Mirrorless Visit Camera Jungle for great value photographic equipment. You can buy, sell or part exchange your own items hassle free & get next day delivery when you do! /proxy.php?image=https://www.camerajungle.co.uk/apple-touch-icon-57x57.png&hash=040c35f19ac3e84cb01ec22a5fdba452&return_error=1 www.camerajungle.co.uk
J2 for £50, J4 for £130
(Assuming the OP hasn't given up by now data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 )