Brown back garden - how best to put in lawn

You will either need to put in some serious drainage - are you surrounded on all sides by gardens or is there somewhere you can direct water to? And improve the soil by introducing more organic matter, but no point doing that without improving drainage. The only alternative would appear to be something like paving, and even then you will need some drainage.

If it is a new house it is just possible that the area has been completely compacted by machinery, and may contain builders' rubbish. That would be easier to sort but you would need to establish what kind of soil you have and if it is compacted. You could try digging a hole maybe 30 - 60 cm across and the same deep and see does water drain out of it, also note as you dig what the condition of the soil is and how solid the sub soil is.

Can you draw a rough plan of the garden giving an idea of the size, any slope on it and what surrounds it? Do your neighbours have similar problems?

If your neighbours don't have any problems and have not had drainage put in or remedial treatment then its unlikely to be a 'claypan' - a layer of impermeable clay maybe 30 to 60cm deep under the topsoil. Does your garden lie lower than those around?

Clay soil is improved by incorporating lots of organic matter - compost, wood chips, manure, bark mulch. Sand is not a good solution to clay, though gravel can help. A load of good, aged wood chips, preferable hardwood, would help though, I can get a good sized trailer load, around 3 to 4 cu metres for €130 delivered locally, so its worth asking round people who do tree and hedge cutting.

Its hard to say where the sub soil would be, can be just a few inches down, could be 30cm or more. Or you may not have much top soil at all. The treatment as above would help create topsoil, along with lots of worms.

You do need to establish whether drainage is needed though, remedial work on the soil will help but you are wasting your time if there is a serious drainage issue.

Edit - its worth saying that any lawn especially one in not great condition will not take kindly to being walked on when wet. If you have walked a track you might be advised to just put down a path. There could be puddles for a while on any lawn immediately after heavy rain, especially on clay soil, so maybe soil improvement would be the solution.