Yes that's 20 - 30 pence per day per employee for an average of soap, paper towels, loo roll. Its just for budgeting purposes only.
You cant say they will only use this much... the reason is because without being rude, one person might use 3 sheets of toilet roll, the other person may use 5 sheets - I am sure you get my drift. The same is said for the paper towels. On average a person may use between 3 - 5 paper towels per visit to the toilet.
As for samples - we send in one roll of loo roll of good quality and a value one and a pack of paper towels. One to watch on paper towels, the cheaper ones don't always fit the dispenser.
On delivery, you get them to sign for the said amount. Say 3 boxes of each. Monitor over the next few months how much they are using. We did this for all our sites that we supply. Never had an issue.
If you really want to get technical, you can get dispensers that feed one sheet at a time! That way the individuals who just waste the products generally get fed up in waiting to get a handful and blocking the toilets or throwing it everywhere if you happen to have that environment.
Purchasing varies on the amount you can purchase so you need to be competitive and buy in bulk to be competitive. Do you have storage? Would you purchase by the pallet or box?
I will email you a few places that possibly could help you but search as well as you may find a better supplier that suits your requirements.
Dave