Hi
I travel to Bali from Australia so can only speak how it is for us. However, we can pay either in Aussie or US $$$ for a 30 day visa.
Getting through the formal procedures depends on how many planes arrive at the same time. I belong to a dedicated Bali travel forum and people often report they get through fairly quick, but someone posted recently that it took 3 hours to get through because lot of planes came in at the same time
When you first arrive follow the crowd, you will be directed to the first queue where you have to pay for your VOA (visa on arrival) then you join the next queue and get the visa stuck in your passport (make sure you have an empty page in your passport for it) After that it's the immigration queue then pick up luggage then another queue for customs. If you find your cases has chalk crosses on it then you will be required to open them... they are looking for extra alcohol.
Cheers Geri

I took US$ and have heard of no-one that has actually paid in £. Doesn't mean it's not possible, but why risk it?

The immigration is really quick, but the VOA is so SLOOOOOOOOW. Be first off your plane and run! Be careful you don't miss the little white box that the booth is!