Which is less than we had before. Also we now have non tariff barriers including a load more red tape bureaucracy even when sending things from one part of the U.K. to another thanks to the Irish Sea border
Yes you can. (Well, at least after covid-19 is over.)
That's been the case since 2014, nothing to do with Brexit.
Before Brexit:
"From 9 June 2014, all British Overseas Territories citizens (BOTCs), British Overseas citizens (BOCs), British Protected Persons (BPPs), and British Subjects (BS) will be allowed to travel visa free to the EU Schengen Area for a maximum of 90 days."
After Brexit:
"If you’re a tourist, you do not need a visa for short trips to most EU countries, Iceland, Liechtenstein, Norway and Switzerland. You’ll be able to stay for up to 90 days in any 180-day period."
UK citizens could move around the EU freely.