Can I take a claim if I have a foreign employer or I am based in another European country?

Claims can be heard against employers who are based outside the UK as long as you are ordinarily resident in the UK. If you are a citizen of another EU country, posted in the UK, you can now claim protection under UK law and submit a claim to an Employment Tribunal or Court. Similarly, if you are a UK national working in an EU country you are covered by their employment protection and can make a claim in their courts.