I think it would be cheaper to largely to do yourself if you or DH are DIY inclined?
Pay someone to get the tarmac up and level the ground but you can chop the dead tree down yourself as close to ground level as possible ready to grow a trailing plant over it later and pull up the plants in the back.
Low maintance to me means long lived perennials and perennials and annuals that self seed and stay compact.
The bulk of my garden is made up of such plants.
If you ensure the ground is weeded, then dump a nice thick layer of compost over it, plant your plants then cover with more compost not many weeds come up.
Google ‘no dig gardening’.
I would personally be cautious about hiring gardeners, as far as I know the industry isn’t tightly regulated.
My mum has hired 3 different ‘professional’ landscape gardeners over the years. None any good!
Her back garden was particularly bad, very steeply sloped and dangerous.
The ‘professional’ gardeners she hired did a lovely job at first glance installing a patio, walled borders, levelling etc.
Then a year or so later it became clear the plant choices were totally wrong - far too big for the space, required frequently pruning which she couldn’t do but much more seriously the cement started coming away from the steps and patio, the wall started falling apart.
It was so dangerous the garden was unusable, my DH (ex builder) ended up rebuilding the entire patio, walls and steps.
She had to pay someone to rip out all the enormous, ridiculous shrubs she couldn’t maintain, I used to prune them when I was over there but I don’t live local anymore.