They would want to limit Imperial ambitious and the size of her surface fleet. It was little Willie's sabre rattling, desire for territory, and desire to build a great navy that got the Brits to back away from them in the years preceeding World War 1. You have to change that attitude for the British to consider making any sort of agreement with them.
Though they are still going to be wary of any one power being dominant on the Continent. So they probably wouldn't outright ally with them.
So, a promise that Germany shall not seek further colonial gains ( more than OTL colonies that is ) and Kaiserliche Marine is set on say 40% of Royal Navy strenghth, would that be enough?