Looking for reasonably priced UK chips (2500ish)

[Juff]

I'm looking at hosting some MTTs in the near future, expecting probably 20-30 people. I have a couple of questions, if anyone could help;

1) Would 2500 chips be enough as long as the denominations/structure were worked out correctly? I'm pretty sure this wouldn't be a problem, but if anyone has tried this and it lead to disaster, advice would be appreciated.

2) Could anyone recommend a cheap UK supplier of suitable chips? Not expecting casino quality, but hopefully something people couldn't grab out of the nearest pound shop to contaminate my supply! Cost is an issue, as I'm footing the bill for this this myself at the moment.

Many thanks for any advice offered.