Have you received samples of the chips from Palm? - I seem to recall in another thread that you were not too impressed with the china clay Pharoahs and, if this is the case, then the clays that PGI have are similar (I believe - I don't have any myself). OR are you going ceramic? When you mention printing aroung the circumference, do you mean on the edge of the chip? - as this is only possible with ceramics not 8v or china clays.
WRT the design, you have 3 options -
Do it yourself if you have the necessary skills - PGI will be able to tell you which formats they accept;
Get PGI to do it in-house for a fee;
Or, start a designer wanted thread. Some excellent designers here who will tell you how much their work will cost to put your ideas on paper. Many have worked with PGI already.
There are a couple of threads on here (probably in the PGI forum) which set out how Joe wants to do business with designs/formats/copyright issues/paperwork required etc following the S!LKS fiasco. I think that they are still valid, but, if you contact Joe at Palm, I'm sure he will tell you exactly what he requires if it is not covered in his forum threads.
One final thing - are you sure your breakdown is correct? Presumably you will be playing 25p/50p cash games with these chips. You may find that you will need more £1 than 25p chips if you play no-limit. I would look to go 100 x 25p; 125 x £1; 75 x £5; or even 60 to 80 x 25p chips depending on how many players you will have (I assume 6 max). You might also want to consider 15 or so £20 chips and reduce the £5 chip numbers to give a larger bank (or does PGI only sell in batches of 25, I can't remember?)
Unless your game plays tight, you can manage with 12 or 16 chips of the lowest denom per player. If your game is limit or lots of min raises, then you may consider more of the 25p chip. Just to give you more things to ponder