What would the Royal Navy do with a Lexington-class carrier?

How would the Royal Navy alter a Lexington-class carrier transferred into British service?

Remove the heavy guns and use the saved topweight and space to improve the ship's carrier capabilities.

The heavy guns should come off the carrier. Their battery puts a large amount of weight high in the ship, where it harms the design more than an equivalent weight lower down. Removing it releases usable space and high weight for aviation equipment or other carrier improvements. The choice separates a hybrid gunship from a carrier optimized around aircraft.