Its a virtual coin so you dont get change, 1 bitcoin is worth over $4000 at moment, so you usually deal with smaller denominations, 0.006btc etc
You can use a plastic or virtual card to buy goods, I use cryptopay and you can get gb pound visa btc cards there and you can bank the bitcoin anytime you want converting it to GBP. I sometimes skim some interest made on the btc back into bank account, pays for a night out...
Its dropped a lot last few weeks, so its a good time to buy as usually it bounces back a lot stronger, reason its dropped is to do with a supposed law in china coming, which looks like it was just made up to caise hysteria, and it actually effects eruthem coin more than BTC even if it does