Very wonky lawn, how to fix?

[Fordian]

My lawn is a bit rubbish. It's 10x4m, suburban estate, 25 yrs old, on clay, Hampshire. It has evidently been laid on old garden beds (visible on old Google earth images!) which have subsided so there's I'd say a good 5" discrepancy in places, more slopes than divots. It's also moss central.

I want to level it.

To add lawn sand etc would probably take a decade, there's so much to fill, and I'd suggest, some scalping of the higher domes to be done.

Should I rotovate the lot and start again? Is that a DIY job? I'd returf rather than reseed, but if I rotovated, incorporated sand, levelled and returfed, I'd imagine that's the ultimate solution.

But would that cost a fortune and be back breaking? Is it a job for a gardener or a landscaper? I'm not sure who to go to!

Your thoughts welcome.

I would definitely pay a landscaper to do it. It’s a time consuming and physically demanding job and you know if it’s mossy then it’s got drainage issues that could do with a bit of sorting. If you can afford to get it done professionally then I would for sure do that.

I'd probably buy a ton of topsoil, fill all the gaps to level it, and leave it for a week to settle, top up and then using a rake, tamp it all down. Then sow grass seed in all the bare patches. The sooner the grass seed is sown the sooner the roots will help to knit it all together but expect some topsoil to wash away if there is a heavy rainfall in the weeks before the seed germinates. You can check the 10 dyay forcast and try to sow when most of the days look good.

If you can do it in April, then you can just sow straight onto the tamped down topsoil.

And keep sowing any bare patches that don't germinate on a weekly basis to get the thickest grass coverage you can.

So might one just smother the underlying grass and plant the topsoil placed over it?

Yes you can do this, but it would be better to spray off the existing lawn first to prevent the weeds etc from coming up through your newly seeded lawn. It is also highly likely the old grass will be a different species to the new seed you will buy and thus it may create a patchy appearance.

Your thoughts welcome.
I think it's one of those 'do it once, do it right' jobs. You mentioned that "to add lawn sand etc would probably take a decade" so it sounds like you intend to be here a while. Try to think of the cost as spread out and in terms of "pounds per year", rather than a one-off cost. It might make it less painful!
Is it a job for a gardener or a landscaper? I'm not sure who to go to!
Speak to the turf supplier, see who they recommend.

Thanks, all.

It needs scraping off, levelling and relaying. Most lawns subside to a degree after 25 years anyway.