Can I go on holiday abroad at 16 by myself ?
You can't travel at 16 without parental consent, and few hotels will let you stay without an adult. So, realistically - no.
Other countries have no need for children of other countries to be wandering around. It can be done if you have an Adult (Your Parents) arrange for an ADULT to be responsible for you in far away place. Getting on a plane and going is the easy part. Getting out of destination Airport is the hard part. Try do it it on your own will usually result in you just being sent back on next flight.
No. You cannot stay at hotels, etc, as an unaccompanied minor child. You have no credit cards in your own name. Highly unlikely you have sufficient funds to pay for everything. If you need a visa, don't expect any unaccompanied minor child to get one.
You can move out with parents permission if you are 16 or over