I have an IPv6 assignment. Am I eligible to receive a /22 of IPv4 address space from the last /8?
No. An LIR must have an IPv6 allocation from the RIPE NCC or an upstream LIR to be eligible to receive a /22 allocation from the last /8.
See section 5.6 of “IPv4 Address Allocation and Assignment Policies for the RIPE NCC Service Region” for more information.