is there anything wrong with just using notes over a chip?
One of my favorite home games I played in college used notes and coin and not chips. We did 25¢ ante hold'em with a $15 max bet or raise. it was loads of fun.
Stacking coins and bills is slower than stacking chips. There's more potential for counting errors as well. But if you don't mind these things potentially slowing the game down, it's actually super fun.
That said, in practice where games are a mix of chips and notes, only notes of the highest denomination would be allowed. Vegas was 100s only on the table before most rooms went to all chips.
A 200 chip set works best as a travel set with a small group and a known stake. You won’t have flexibility to cover multiple stakes nor are you able to support a “full” table.
This is the best description. And you do have to change your thinking about set design when limiting the quantity.
I'm thinking 6 max NLHE 25p/25p
100x 25p
100 x £1
And £5 notes
For 6-max, you are at least looking at an average of 33 chips per player which is workable. But I would not put half your capacity into blind chips. I would suggest a drop down to 60 * 25p and leave 140 for £1 chips. The £1 would be the natural "workhorse" at these stakes. Everyone then will have more than one barrel of workhorse chips to work with. The blind chips tend to sit in stacks and only get use on early streets anyway. This setup wouldn't be unreasonable for 7-handed either. (However, I would think 8-handed would be pushing it.)
Bottom line, at 6-max an "average" stack would contain a little more than £25 worth of chips (in quarters and singles, of course) and just need be augmented by £5 notes depending on how big you want the game to play. In the thought experiment at least, that seems very doable.
With your breakdown, the average would be a little more than £20 worth of chips and half of the quantity would be in quarters.
Also, I would be strict about only £5 notes playing to avoid confusion with higher notes. (And also any higher notes with these stakes would constantly have to be broken an inconvenient number of times.)
But I would say doable, but as I said, cut the blind chips way down to make room for more useful singles.