Problem with the timber yards is that for Joe and Jane Public (including me), they're rather .... I need a word that's a cross between awkward and intimidating.
With B&Q or Woodies, you can potter about, find things you're looking for without hassle, check prices readily on the website or on the shelf, and don't need to have an exact list in mind when you go in (so you might go in to get some sandpaper and on the way pick up some beeswax that you've been meaning to stock up on 'cos the tin's almost gone in the shed, and I could use a length or so of 2x1/2 for some scrap uses, and a half-sheet of 18mm ply would let me do that thing next weekend...
Or, you just go in, take a look at what timber they have, and as you're looking at it, figure out "that'd be good for this kind of project" and buy some of that; some of us do this for a hobby, it's not like we're on a commission - we just do what feels like fun. So if the available timber says a table, build that; and if it says a birdfeeder, build that. But you have to look before you buy for that kind of approach.
Can't do that in Chadwicks really. And can't gauge the price ahead of time without ringing up and engaging with them to get a quote and they're expecting you to be ordering commercial quantities instead of a sheet or two and they're expecting you to have at least a van that can carry full 4.8m lengths or 8x4 sheets, if all you have as Joe Public is a normal family car then you're pretty much hosed.
Honestly, if the timber merchants wanted to, they could steal every last wood-buying customer from the big box stores with not much effort. They're even trying that over here with crowds like buildwithme.ie and build4less.ie which are just front-end websites to builder's merchants. And one or two merchants are actually starting to put together websites that let you see what they have for sale.
But honestly, how hard would it be for them to say "Right, if you're a DIY-er or whatever, our amateur hours are from 10am to 1pm on Saturday. Show up then, you're welcome"? I mean, it's not like we want to get underfoot in a commercial yard...