What size garden are we talking about Bibba? You're right that lawn takes a lot of looking after if it's not going to look a proper mess. I've got rid of all grass except about 6 square feet round the twirly washing line and have laid concrete slabs. They're not all that expensive - I paid under £2 each for 450mm square ones. Go to a local builders merchants to get them - I found them much cheaper than garden centres. I laid mine on earth with no preparation other than levelling it carefully, or you could use some sand to bed them on. That meant a lot of work on my knees, so you may need to get someone to do it for you.

Shrubs are much less work than flower beds once they are established, and tough hardy perennials are less work than annuals and biennials.
Plants like hardy geraniums, aquilegia, epimedium, day lilies, narcissi and daffs, euphorbias, michaelmas daisies (and many others) will look attractive with very little attention.

Supermarkets are a good source of cheap commonly found plants. You won't find any rarities, but from time to time they have them & can be a source of space fillers.

And keep your eyes open at car boot sales. The seller probably won't be able to give you much info about the plant - "white flowers in spring" will be the sort of info, if you're lucky, but they'll be cheap, so worth a punt.

Alternative to slabs is a weed membrane covered with a good 6 inches of gravel and then tubs and troughs so you don't have to bend down so far - or even raised beds.

I also was going to suggest large size gravel (so the cats dont use it) on a double membrane, shrubs and or containers look good and are easier to maintain. also the odd large stone, bird bath, bird feeding station can add interest and you still feel that you have a garden. Your local 'free cycle' may have garden items such as tubs etc which would be free so worth a try.
How about Artificial Grass the cheapest online in the UK seems to be available in 2m & 4m Widths at £5.99 per square meter inclusive of VAT and delivery is free.
There are pages of photos of gardens done by members on here who have tackled this problem why not scroll down and have a look at pages such as back 'Back garden ideas, and side garden ideas'.
Good luck you can still have a nice garden and I hope you will post some photos of what you do do.

Not sure where you live but if you are anywhere near me (east Yorkshire) I would come and have a look for you ... no charge, I am a self employed gardener. If the area is reasonably small and you provided all the plants etc that you need I would do the work for free. You can send a private message if you do not wish to disclose where you live.