I am a UK passport holder, will I need a visa for Europe?
Not certain, and this relates to a separate tussle between the Commission and European Parliament on No Deal arrangements. Check back here later
As someone working on this on the EU side, could I just clarify that there isn't a tussle between the Commission and Parliament. It's a specific issue with Spain (therefore EU member states vs Parliament), as they are currently blocking this due to how Gibraltar is legally referenced in the text. If it is not agreed this week at least informally, and if no deal goes ahead on 12th, then there will be no blanket visa-exemption for UK citizens to the Schengen area. In theory this means a visa would be required.
However, I don't expect this blocking to continue and expect that there will be an agreement. It's about 99% certain that there will be a blanket visa exemption for UK citizens travelling to Schengen.
As for ETIAS, from 2021 all non-EU nationals (aside from nationals of Schengen countries not in EU) will have to apply for an ETIAS at a cost of €7. More or less the same as an ESTA.
Also happy to answer or try to get clearer answers for specific legal questions on no-deal contingency plans if needed.