In a recent experiment carried out on SURF we have shown that on addition of ethanol to a DPPC model membrane, the anaesthetic initially diffuses to the bilayer surface followed by a slower insertion into the lipid head groups. It is expected that addition of cholesterol to the biomembrane will act in competition with this ethanol penetration at the interface, likely slowing the rate of adsorption. Therefore, we propose utilising the higher flux and larger single angle Q range available on the new INTER reflectometer to fully resolve the apparent two stage mechanism by which ethanol inserts into the bilayer and study the effect of varying cholesterol content on the rate at which this occurs.