Do I need separate estate planning documents for Israel and my home country?

Yes, in virtually every case. Israeli legal instruments cover Israeli-situated assets and are recognised by Israeli institutions. Your home-country will, lasting power of attorney, or living trust covers your home-country assets. The two sets of documents must be coordinated — ideally by attorneys in both jurisdictions who communicate with each other — to ensure they are consistent and do not inadvertently revoke each other. For example, an Israeli will that says "this revokes all previous wills" could be read to revoke your US or UK will if poorly drafted. A competent Israeli attorney will include a clause limiting the scope of the Israeli will to Israeli assets.