Apologies for the ramble, this is the short version
😂I hate to be the bearer of more bad news than you already know @FictionalCharacter but finding the right kind of gardener is increasingly difficult and frustrating to pin someone down with a commitment, so I'd be very clear with whoever you ask to quote, on exactly what you're expecting them to do.
Be prepared for lots of false starts, people letting you down, etc. my advice is to do your garden project in two stages. Garden clearance first, then regular gardening help, you may not get one person to do it all.
Realistically there tend to be 3 categories of gardening companies/individual
1 - 2 days Blitz = circa £200 - £300 but it depends on the size and state of your garden.
Regular skilled gardener once a week visit = £60 to £80 per visit, grass and weeding plus general jobs. Warning: these people are highly in demand, tend to stick to landscaping jobs, rarely want to do all the hard graft every week.
Regular semi-skilled or jobbing gardeners = £49 - £50 per visit - in the majority, nowadays they just want to push a mower up and down, and onwards to next customer, as they can cover more people than focusing on fewer customers with all the whistles and bells. They don't know one end of pruning sheers from the other, but they get the absolute basics done.
Now a bit more detail....
One-off garden clearance, grounds work type companies. They are good at doing one-off jobs, come in with the right tools and make short work of it. After that, they aren't interested in ongoing maintenance. You may have to part with circa £200-£300 (caveat: highly dependent on the size and the state of your garden) - benefit is they will blitz your garden back to being a blank canvas, very quickly, so you have time in this growing season to enjoy the tidiness and do some planting. Downside is that you need to keep it tidy from then on by identifying a different person for regular maintenance.
Fully qualified horticultural trained, are experts and know a lot about plants, will charge a premium, and don't want to be tied to a weekly customer regime or do the grunt work.
Jobbing gardeners I've approached in the past say "sorry I don't do weeding"
and they are often unreliable, don't show up so you text them and they say "the van's got a puncture/sorry not feeling well, can't be arsed see you next week". Cheers.
I now have a lovely chap, really reliable and helps with most general gardening work, and I "keep him close with hoops of steel" (to paraphrase Shakespeare) because he's a very very rare person. I value him highly so he gets cups of tea and biscuits during his 3-4 hours a week! He costs me £50 for 3 hrs (Glos area) and worth every penny.