Wirral Archives have copies of building plans for Wallasey dating back to the 1870s; they don't have a complete set but it's possible the one you're after may have survived. If you email a request to them, giving as many details as you can, at
[email protected] they should be able to look for it for you, and if it still exists provide you with a copy, either hard-copy or by email, for a small charge.